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Full text of "Soap-making manual; a practical handbook on the raw materials, their manipulation, analysis and control in the modern soap plant"

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r 



■^^■ta 



• o -• ■* , *" 



Soap-Making Manual 

A practical handbook on the raw 
materials, their manipulation, anal- 
ysis and control in the modern 
soap plant. 



By 
E. G. Thomssetiy Ph. D, 



ILLUSTRATED 




NEW YORK 

D. VAN NOSTRAND COMPANY 

Eight Warren Street 

1922 



r 



• - • • , 

•\ : : >•; . . 



■ <^^ 

^ ^ 



.'/ I J 



COPYKIGHT 1922 

By 
D. VAN NOSTRAND COMPANY 



Printed in the United States of America 



»4 



PREFATORY NOTE. 



The material contained in this work appeared sev- 
eral years ago in serial form in the American Perfumer 
and Essential Oil Review. Owing to the numerous re- 
quests received, it has been decided to now place before 
those interested, these articles in book form. While it 
is true that the works pertaining to the soapmaking 
industry are reasonably plentiful, books are quite rare, 
however, which, in a brief volume, will clearly outline 
the processes employed together with the neces- 
sary methods of analyses from a purely practical 
standpoint. In the work presented the author has 
attempted to briefly, clearly, and fully explain the 
manufacture of soap in such language that it might be 
understood by all those interested in this industry. In 

I many cases the smaller plants find it necessary to dis- 

pense with the services of a chemist, so that it is neces- 

I sary for the soapmaker to make his own tests. The 

tests outlined, therefore, are given as simple as possi- 

l ble to meet this condition. The formulae submitted 

^ are authentic, and in many cases are now being used 

\ in soapmaking. 

In taking up the industry for survey it has been thought 
desirable to first mention and describe the raw materials 
used; second, to outline the processes of manu- 
facture; third, to classify the methods and illustrate 
by formulae the composition of various soaps together 
with their mode of manufacture; fourth, to enumerate the 
various methods of glycerine recovery, including the 
processes of saponification, and, fifth, to give the most im- 
portant analytical methods which are of value to control 

in 

er cr * r" "^ "'v 



the process of manufacture and to determine the purity 
and fitness of the raw material entering into it 

It is not the intention of the author to go into great 
detail in this work, nor to outline to any great extent the 
theoretical side of the subject, but rather to make the work 
as brief as possible, keeping the practical side of the sub- 
ject before him and not going into concise descriptions of 
machinery as is very usual in works on this subject. 
Illustrations are merely added to show typical kinds 
of machinery used. 

The author wishes to take this opportunity of thank- 
ing Messrs. L. S. Levy and E. W. Drew for the reading 
of proof, and Mr. C. W. Aiken of the Houchin-Aiken Co., 
for his aid in making the illustrations a success, as 
well as others who have contributed in the compil- 
ing of the formulae for various soaps. He trusts that 
this work may prove of value to those engaged in soap 
manufacture. 

E. G. T. 
January, 1922 



IV 



TABLE OF CONTENTS. 



CHAPTER I. 
Raw Materials Used in Soap Making 

1. Soap Defined , .' . 

2. Oils and Fats 

3. Saponification Defined 

4. Fats and Oils Used in Soap Manufacture 

Fullers* Earth Process for Bleaching Tallow 

Method for Further Improvement of Color in Tallow 

Vegetable Oils 

Chrome Bleaching of Palm Oil 

Air Bleaching of Palm Oil 

5. Rancidity of Oils and Fats 

Prevention of Rancidity 

6. Chemical Constants of Oils and Fats 

7. Oil Hardening or Hydrogenating 

8. Grease 

9. Rosin (Colophony, Yellow Rosin, Resina) 

10. Rosin Saponification 

1 1. Naphthenic Acids 

12. Alkalis 

Caustic Soda 

Caustic Potash 

Sodium Carbonate (Soda Ash) 

Potassium Carbonate .' 

13. Additional Material Used in Soap Making 

CHAPTER II. 
Construction and Equipment of a Soap Pi-ant 



Page. 


1- 


30 




1 


1- 


2 


2- 


3 


3- 


4 


4- 


6 




6 


6- 


9 


9- 


12 


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16 


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18 




18 


18- 


19 


19- 


21 


21- 


22 


22- 


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23- 


24 


24- 25 


25- 


26 




26 


26- 


28 


28- 


29 




29 


29- 


30 



31- 34 



CHAPTER III 

Classification of Soap Making Methods 35- 46 

1. Full Boiled Soaps 36- 42 

2. Cold Process 43- 44 

3. Carbonate Saponification 45- 46 

CHAPTER IV. 
Classification of Soaps 47-104 

1. Laundry Soap 48 

Semi-Boiled Laundry Soap .• 49- 50 

Settled Rosin Soap SO- 54 

2. Chip Soap 54-55 



7 



SOAP-MAKING MANUAL 

Page. 

Cold Made Ckip Soap 55- 56 

Unfilled Chip Soap 56 

J. Soap Powders ^ 56- 59 

Li^ht Powders 60- 61 

4. Scouring Powders 61 

5. Scouring Soap 61- 62 

6. Floating Soap 62- 65 

7. Toilet Soap 65- 68 

Cheaper Toilet Soaps 6b- 69 

Run and Glued-up Soaps 69- 71 

Curd Soap 71- 72 

Cold Made Toilet Soaps 72- 73 

Perfuming and Coloring Toilet Soaps 73- 75 

Coloring Soap 75- 76 

8. Medicinal Soaps 76- 11 

Sulphur Soaps 11 

Tar Soap 11 

Soaps Containing Phenols 11' 78 

Peroxide Soap 78 

Mercury Soaps 78 

Less Important Medicinal Soaps 78- 79 

9. Castile Soap 79- 81 

10. Eschweger Soap 81- 82 

1 1. Transparent Soap 82- 84 

Cold Made Transparent Soap 84- 87 

12. Shaving Soaps 87- 90 

Shaving Powder 90 

Shaving Cream 90- 93 

13. Pumice or Sand Soaps 93- 94 

14. Liquid Soaps 94-95 

15. Use of Hardened Oils ip Toilet Soaps 96- 98 

16. Textile Soaps 98 

Scouring and Fulling Soaps for Wool 98-100 

Wool Thrower's Soap 100-101 

Worsted Finishing Soaps 101 

Soaps Used in the Silk Industry 101-103 

Soaps Used for Cotton Goods 103-104 

17. Sulphonated Oils 104-105 

CHAPTER V. 

GlyCIKINB RlCOVBBY 105-126 

1. Methods of Saponification 105-106 

VI 



TABLE OF CONTENTS 

Page. 

RecoTery of Glycerine from Spent Lye 106<U3 

Twifbkell Process 113-U8 

Antoclaye Saponification 118 

Lime Saponification 1 18420 

Acid Saponification 120-121 

Aqueons Saponification 121 

Splittingr Fats with Ferments 12M23 

KrcbiU Process 123*125 

2. Distillation of Fatty Acids 125-126 

CHAPTER VL 

Analytical Methods 127-164 

1. Analysis of Oils and Fats 128 

Free Fatty Acids 128-130 

Moisture 130 

Titer 130-132 

Determination of Unsaponifiable Matter 132-133 

Test for Color of Soap 133-134 

Testing of Alkalis Used in Soap Making 134-137 

2. Soap Analysis 137-138 

Moisture 138-139 

Free Alkali or Acid 139-142 

Insoluble Matter 143 

Starch and Gelatine 143-144 

Total Fatty and Resin Acids 144 

Determination of Rosin 144-147 

Total Alkali 147-148 

Unsaponifiable Matter 148 

Silica and Silicates 148-149 

Glycerine in Soap 149-150 

Sugar in Soap 150 

3. Glycerine Analysis 15<S151 

Sampling ISl 

Analysis 151-154 

Acetin Process for the Determination of Glycerol. .. .155-156 

The Method 156-159 

Ways of Calculating Actual Glycerol Contents 159-160 

Bichromate Process for Glycerol Determination Re- 
agents Required 160-161 

The Method 161-162 

Sampling Crude Glycerine 162-164 

VII 



SOAP-MAKING MANUAL 

CHAPTER VII Page. 

Standard Methods for thb Sampling and Analysis of 

Commercial Fats and Oils 165-195 

1. Scope, Applicability and Limitations of the Methods. .165-166 

Scope , . 165 

Applicability 166 

Limitations 166 

Sampling 166-169 

Tank Cars 166-167 

Barrels, Tierces, Casks, Drums, and Other Packages. 168 

2. Analysis 169-183 

Sample 169 

Moisture and Volatile Matter 170-172 

Insoluble Impurities 172-173 

Soluble Mineral Matter 173 

Free Fatty Acids 174 

Titer 174-175 

Unsaponifiable Matter 176-177 

Iodine Number- Wijs Method 177-181 

Saponification Number (Koettstorfer Number) 181 

Melting Point 1&1-182 

Cloud Test 182-184 

3. Notes of the Above Methods 184-196 

Sampling 183 

Moisture and Volatile Matter 184-187 

Insoluble Impurities 187 

Soluble Mineral Matter 187-188 

Free Fatty Acid 188-189 

Titer 189 

Unsaponified Matter 190-193 

Melting Point 193-196 

Plant and Machinery 198-219 

Illustrations of Machinery and Layouts of the Plant 

of a Modern Soap Making Establishment 198-219 

Appendix 219-237 

Useful Tables 

Index ,. 239 



VIII 




* - • i. c • 

* ' • - ^ ! ' - ' " - * 






• ■ k • ( «. 






CHAPTER I 

Raw Materials Used in Soap Maldng. 

Soap is ordinarily thought of as the common cleansing 
agent well known to everyone. In a general and strictly 
chemical sense this term is applied to the salts of the non- 
volatile fatty acids. These salts are not only those formed 
by the alkali metals, sodium and potassium, but also those 
formed by the heavy metals and alkaline earths. Thus 
we have the insoluble soaps of lime and magnesia formed 
when we attempt to wash in "hard water"; again alum- 
inum soaps are used extensively in polishing materials 
and to thicken lubricating oils; ammonia or "benzine" 
soaps are employed among the dry cleaners. Commonly, 
however, when we speak of soap we limit it to the sodium 
or potassium salt of a higher fatty acid. 

It is very generally known that soap is made by com- 
bining a fat or oil with a water solution of sodium hydrox- 
ide (caustic soda lye), or potassium hydroxide (caustic 
potash). Sodium soaps are always harder than potassium 
soaps, provided the same fat or oil is used in both cases. 

The detergent properties of soap are due to the fact 
that it acts as an alkali regulator, that is, when water 
comes into contact with soap, it undergoes what is called 
hydrolytic dissociation. This means that it is broken 
down by water into other substances. Just what these 
substances are is subject to controversy, though it is pre- 
sumed caustic alkali and the acid alkali salt of the fatty 
acids are formed. 

OILS AND FATS. 

There is no sharp distinction between fat and oil. By 
"oil" the layman has the impression of a liquid which at 

1 



^ -..,.• - ,SQAP-MAKING MANUAL 

warm temperature will Hdw as a slippery, lubricating, vis- 
cous fluid; by "fat" he understands a greasy, solid sub- 
stance unctuous to the touch. It thus becomes necessary 
to differentiate the oils and fats used in the manufacture 
of soap. 

Inasmuch as a soap is the alkali salt of a fatty acid, the 
oil or fat from which soap is made must have as a con- 
stituent part, these fatty acids. Hydrocarbon oils or par- 
affines, included in the term "oil," are thus useless in the 
process of soap-making, as far as entering into chemical 
combination with the caustic alkalis is concerned. The 
oils and fats which form soap are those which are a com- 
bination of fatty acids and glycerine, the glycerine being 
obtained as a by-product to the soap-making industry. 

NATURE OF A FAT OR OIL USED IN SOAP MANUFACTURE. 

Glycerine, being a tryhydric alcohol, has three atoms of 
hydrogen which are replaceable by three univalent radicals 
of the higher members of the fatty acids, e. g., 

OH OR 

C, H« OH + 3 ROH = C H5 OR + 3 H,0 
OH OR 

Glycerine plus 3 Fatty Alcohols equals Fat or Oil plus 

3 Water. 
Thus three fatty acid radicals combine with one glycer- 
ine to form a true neutral oil or fat which are called 
triglycerides. The fatty acids which most commonly en- 
ter into combination of fats and oils are lauric, myristic, 
palmitic, stearic and oleic acids and form the neutral oils 
or triglycerides derived from these, e. g., stearin, palmatin, 
olein. Mono and diglycerides are also present in fats. 

SAPONIFICATION DEFINED. 

When a fat or oil enters into chemical combination with 
one of the caustic hydrates in the presence of water, the 



RAW MATERIALS 

process is called "saponification" and the new compoondt 
formed are soap and glycerine, thus: 

OR OH 

QH. OR + 3 NaOH = CA OH + 3 NaOR 
OR OH 

Fat or Oil plus 3 Sodium Hydrate equals Glycerine plus 

3 Soap. 
It is by this reaction almost all of the soap used today 
is made. 

There are also other means of saponification, as, the 
hydrolysis of aA oil or fat by the action of hydrochloric 
or sulfuric acid, by autoclave and by ferments or en- 
zymes. By these latter processes the fatty acids and 
glycerine are obtained directly, no soap being formed. 

FATS AND OILS USED IN SOAP MANUFACTURE. 

The various and most important oils and fats used in 
the manufacture of soap are, tallow, cocoanut oil, palm 
oil, olive oil, poppy oil, sesame oil, soya bean oil, cotton- 
seed oil, corn oil and the various greases. Besides these 
the fatty acids, stearic, red oil (oleic acid) are more or 
less extensively used. These oils, fats and fatty acids, 
while they vary from time to time and to some extent as 
to their color, odor and consistency, can readily be distin- 
guished by various physical and chemical constants. 

Much can be learned by one, who through continued 
acquaintance with these oils has thoroughly familiarized 
himself with the indications of a good or bad oil, by 
taste, smell, feel and appearance. It is, however, not well 
for the manufacturer in purchasing to depend entirely upon 
these simpler tests. Since he is interested in the yield of 
glycerine, the largest possible yield of soap per pound of 
soap stock and the general body and appearance of the 
finished product, the chemical tests upon which these de- 



SOAP-MAKING MANUAL 

pend should be made. Those especially important are the 
acid value, percentage unsaponifiable matter and titer test. 

A short description of the various oils and fats men- 
tioned is sufficient for their use in the soap industry. 

Tallow is the name given to the fat extracted from the 
solid fat or "suet" of cattle, sheep or horses. The quality 
varies greatly, depending upon the seasons of the year, 
the food and age of the animal and the method of ren- 
dering. It comes to the market under the distinction of 
edible and inedible, a further distinction being made in 
commerce as beef tallow, mutton tallow or horse tallow. 
The better quality is white and bleaches whiter upon ex- 
posure to air and light, though it usually has a yellowish 
tint, a well defined grain and a clean odor. It consists 
chiefly of stearin, palmitin and olein. Tallow is by far the 
most extensively used and important fat in the making 
of soap. 

In the manufacture of soaps for toilet purposes, it is 
usually necessary to produce as white a product as pos- 
sible. In order to do this it often is necessary to bleach 
the tallow before saponification. The method usually em- 
ployed is the Fuller's Earth process. 

fuller's earth process for bleaching tallow. 
From one to two tons of tallow are melted out into the 
bleaching tank. This tank is jacketed, made of iron and 
provided with a good agitator designed to stir up sediment 
or a coil provided with tangential downward opening per- 
forations and a draw-off cock at the bottom The coil is 
the far simpler arrangement, more cleanly and less likely 
to cause trouble. By this arrangement compressed air 
which is really essential in the utilization of the press 
(see later) is utilized for agitation. A dry steam coil in 
an ordinary tank may be employed in place of a jacketed 
tank, which lessens the cost of installatioa 



RAW MATERIALS 

The tallow in the bleaching tank is heated to 180* F. 
(82'' C.) and ten pounds of dry salt per ton of fat used 
added and thoroughly mixed by agitation. This addition 
coagulates any albumen and dehydrates the fat. The 
whole mass is allowed to settle over night where possible, 
or for at least five hours. Any brine which has separated is 
drawn off from the bottom and the temperature of the 
fat is then raised to 160** F. {7V C). 

Five per cent, of the weight of the tallow operated 
upon, of dry Fuller's earth is now added and the whole 
mass agitated from twenty to thirty minutes. 

The new bleached fat, containing the Fuller's earth is 
pumped directly to a previously heated filter press and 
the issuing clear oil run directly to the soap kettle. 

One of the difficulties experienced in the process is the 
heating of the press to a temperature sufficient to prevent 
solidification of the fat without raising the press to too 
great a temperature. To overcome this the first plate is 
heated by wet steam. Air delivered from a blower and 
heated by passage through a series of coils raised to a 
high temperature by yexternal application of heat (super- 
heated steam) is then substituted for the steam. The 
moisture produced by the condensation of the steam is 
vaporized by the hot air and carried on gradually^to each 
succeeding plate where it again condenses and vaporizes. 
In this way the small quantity of water is carried through 
the entire press, raising its temperature to SO^-lOO** C. 
This temperature is subsequently maintained by the 
passage of hot air. By this method of heating the poor 
conductivity of hot air is overcome through the inter- 
mediary action of a liquid vapor and the latent heat of 
steam is utilized to obtain the initial rise in temperature. 
To heat a small press economically where conditions are 
such that a large output is not required the entire press 



SOAP-MAKING MANUAL 

may be encased in a small wooden house which can be 
heated by steam coils. The cake in the press is heated for 
some time after the Alteration is complete to assist drain- 
age. After such treatment the cake should contain ap- 
proximately 15 per cent fat and 25 per cent, water. The 
cake is now removed from the press and transferred to a 
small tank where it is treated with sufficient caustic soda 
to convert the fat content into soap. 

Saturated brine is then added to salt out the soap, the 
Fuller's earth is allowed to settle to the bottom of the 
tank and the soap which solidifies after a short time is 
skimmed off to be used in a cheap soap where color is 
not important. The liquor underneath may also be run 
off without disturbing the sediment to be used in grain- 
ing a similar cheap soap. The waste Fuller's earth con- 
tains about 0.1 to 0.3 per cent, of fat. 

METHOD FOR FURTHER IMPROVEMENT OF COLOR. 

A further improvement of the color of the tallow may 
be obtained by freeing it from a portion of its free fatty 
acids, either with or without previous Fuller's earth 
bleaching. 

To carry out this process the melted fat is allowed to 
settle and as much water as possible taken off. The tem- 
perature is then raised to 160** F. with dry steam and 
enough saturated solution of soda ash added to remove 
0.5 per cent, of the free fatty acids, while agitating the 
mass thoroughly mechanically or by air. The agitation 
is continued ten minutes, the whole allowed to settle for 
two hours and the foots drawn off. The soap thus formed 
entangles a large proportion of the impurities of the fat. 

VEGETABLE OILS. 

Coc0anut Oil, as the name implies, is obtained from the 
fruit of the cocoanut palm. This oil is a solid, white fat at 
ordinary temperature, having a bland taste and a charac- 

6 



RAW MATERIALS 

teristic odor. It is rarely adulterated and is very readily 
saponified. In recent years the price of this oil has in- 
creased materially because cocoanut oil is now being used 
extensively for edible purposes, especially in the making of 
oleomargarine. Present indications are that shortly very 
little high grade oil will be employed for soap manufacture 
since the demand for oleomargarine is constantly increas- 
ing and since new methods of refining the oil for this pur- 
pose are constantly being devised. 

The oil is found in the market under three different 
grades: (1) Cochin cocoanut oil, the choicest oil comes 
from Cochin (Malabar). This product, being more care- 
fully cultivated and refined than the other grades, is 
whiter, cleaner and contains a smaller percentage of free 
acid. (2) Ceylon cocoanut oil, coming chiefly from Cey- 
lon, is usually of a yellowish tint and more acrid in odor 
than Cochin oil. (3) Continental cocoanut oil (Copra, 
Freudenberg) is obtained from the dried kernels, the copra, 
which are shipped to Europe in large quantities, where the 
oil is extracted. These dried kernels yield 60 to 70 per 
cent oil. This product is generally superior to the Ceylon 
oil and may be used as a very satisfactory substitute for 
Cochin oil, in soap manufacture, provided it is low in free 
acid and of good color. The writer has employed it satis- 
factorily in the whitest and finest of toilet soaps without 
being able to distinguish any disadvantage to the Cochin 
oil. Since continental oil is usually cheaper than Cochin 
oil, it is advisable to use it, as occasion permits. 

Cocoanut oil is used extensively in toilet soap making, 
usually in connection with tallow. When used alone 
the soaf made from this oil forms a lather, which comes 
up rapidly but which is fluffy and dries quickly. A pure 
tallow soap lathers very much slower but produces a more 
lasting lather. Thus the advantage of using cocoanut oil 



/" 



SOAP-MAKING MANUAL 

in soap is seen. It is further used in making a cocoanut 
oil soap by the cold process also for "fake" or filled soaps. 
The fatty acid content readily starts the saponification 
which takes place easily with a strong lye (25**-35** B.). 
Where large quantities of the oil arc saponified care must 
be exercised as the soap formed suddenly rises or puffs 
up and may boil over. Cocoanut oil soap takes up large 
quantities of water, cases having been cited where a 500 
per cent, yield has been obtained. This water of course 
dries out again upon exposure to the air. The soap is 
harsh to the skin, develops rancidity and darkens readily. 

Palm Kernel Oil, which is obtained from the kernels of 
the palm tree of West Africa, is used in soap making to re- 
place cocoanut oil where the lower price warrants its use. 
It resembles cocoanut oil in respect to saponification and 
in forming a very similar soap. Kernel oil is white in 
color, has a pleasant nutty odor when fresh, but rapidly 
develops free acid, which runs to a high percentage. 

Palm Oil is produced from the fruit of the several species 
of the palm tree on the western coast of Africa generally, 
but also in the Philippines. The fresh oil has a deep orange 
yellow tint not destroyed by saponification, a sweetish taste 
and an odor of orris root or violet which is also imparted 
to soap made from it. The methods by which the natives 
obtain the oil are crude and depend upon a fermentation, or 
putrefaction. Large quantities are said to be wasted be- 
cause of this fact. The oil contains impurities in the form 
of fermentable fibre and albuminous matter, and conse- 
quently develops free fatty acid rapidly. Samples tested 
for free acid have been found to have hydrolized completely 
and one seldom obtains an oil with low acid content 
Because of this high percentage of free fatty acid, the 
glycerine yield is small, though the neutral oil should 
produce approximately 12 per cent, glycerine. Some 



t 



RAW MATERIALS 

writers claim that glycerine exists in the free state in palm 
oil. The writer has washed large quantities of the oil and 
analyzed the wash water for glycerine. The results showed 
that the amotmt present did not merit its recovery. Most 
soap makers do not attempt to recover the glycerine 
from this oil, when used alone for soap manufacture. 

There are several grades of palm oil in commerce, but 
in toilet soap making it is advisable to utilize only Lagos 
palm oil, which is the best grade. Where it is desired to 
maintain the color of the soap this oil produces, a small 
quantity of the lower or "brass" grade of palm oil may be 
used, as the soap made from the better grades of oil 
gradually bleaches and loses its orange yellow color. 

Palm oil produces a crumbly soap which cannot readily 
be milled and is termed "short." When used with tallow 
and cocoanut oil, or 20 to 25 per cent, cocoanut oil, it 
produces a very satisfactory toilet soap. In the saponifi- 
cation of palm oil it is not advisable to combine it with 
tallow in the kettle, as the two do not readily mix. 

Since the finished soap has conveyed to it the orange 
color of the oil, the oil is bleached before saponification. 
Oxidation readily destroys the coloring matter, while heat 
and light assist materially. The methods generally cm- 
ployed are by the usr of oxygen developed by bichromates 
and hydrochloric add and the direct bleaching through 
the agency of th«« nxy«rn nf tlie air. 

CHIW)Mtt «l,ftA( MlN(i OP PALM OIL. 

The chrome pror<*M of Idrarlilng palm oil is more rapid 
and the oxygen tliiu dt*rlvrd bring mnrc active will bleach 
oils which air alone cannot It dependN upon the reaction: 

Na.CrA + filial f'r.d, ( 2Na(:i + 70. 
in which th« oxygen is the wptlvr principle. In practice it 
is found necessary to i\kv m\ txccmm of acid over that 
theoretically indicated. 

f 



SOAP-MAKING MANUAL 

For the best results an oil should be chosen containing 
under 2 per cent, impurities and a low percentage of free 
fatty acids. Lagos oil is best adapted to these requirements. 
The oil is melted by open steam from a jet introduced 
through the bung, the melted oil and condensed water run- 
ning to the store tank through two sieves (about }i inch 
mesh) to remove the fibrous material and gross imparities 
The oil thus obtained contains fine earthy and fibrous ma- 
terial and vegetable albuminous matter which should be 
removed, as far as possible, since chemicals are wasted in 
their oxidation and they retard the bleaching. This is best 
done by boiling the oil for one hour with wet steam and 
10 per cent, solution of common salt (2 per cent, dry salt 
on weight of oil used) in a lead-lined or wooden tank. 
After settling over night the brine and impurities are re- 
moved by running from a cock at the bottom of the vat 
and the oil is run out into the bleaching tank through an 
oil cock, situated about seven inches from the bottom. 

The bleaching tank is a lead-lined iron tank of the ap- 
proximate dimensions of 4 feet deep, 4 feet long and 
314 feet wide, holding about 1^ tons. The charge 
is one ton. A leaden outlet pipe is fixed at the bottom, to 
which is attached a rubber tube closed by a screw clip. A 
plug also is fitted into the lead outlet pipe from above. 
Seven inches above the lower outlet is affixed another tap 
through which the oil is drawn off. 

The tank is further equipped with a wet steam coil and a 
coil arranged to allow thorough air agitation, both coils 
being of lead. A good arrangement is to use one coil to 
deliver either air or steam. These coils should extend as 
nearly as possible over the entire bottom of the tank and 
have a number of small downward perforations, so as to 
spread the agitation throughout the mass. 

The temperature of the oil is reduced by passing in aii 

10 



RAW MATERIALS 

to 110° F. and 40 pounds of fine common salt per ton added 
through a sieve. About one-half of the acid (40 pounds 
of concentrated commercial hydrochloric acid) is now 
poured in and this is followed by the sodium bichromate 
in concentrated solution, previously prepared in a small 
lead vat or earthen vessel by dissolving 17 pounds of bi- 
chromate in 45 pounds commercial hydrochloric acid. This 
solution should be added slowly and should occupy three 
hours, the whole mass being thoroughly agitated with aii 
during the addition and for one hour after the last of the 
bleaching mixture has been introduced. The whole mix- 
ture is now allowed to settle for one hour and the ex- 
hausted chrome liquors are then run off from the lowei 
pipe to a waste tank. About 40 gallons of water are now 
run into the bleached oil and the temperature raised by 
open steam to 150** to 160° F. The mass is then allowed 
to settle over night. 

One such wash is sufficient to remove the spent chrome 
liquor completely, provided ample time is allowed foi 
settling. A number of washings given successively with 
short periods of settling do not remove the chrome liquors 
effectually. The success of the operation depends en- 
tirely upon the completeness of settling. 

The wash water is drawn off as before and the clear 
oil run to storage tanks or to the soap kettle through the 
upper oil cock. 

The waste liquors are boiled with wet steam and the oil 
skimmed from the surface, after which the liquors are run 
out through an oil trap. 

By following the above instructions carefully it is pos- 
sible to bleach one ton of palm oil with 17 pounds of bi- 
chromate of soda and 85 pounds hydrochloric acid. 

The spent liquors should be a bright green color. Should 
they be of a yellow or brownish shade insufficient acid has 

11 



SOAP-MAKING MANUAL 

been allowed and more must be added to render the whole 
of the oxygen available. 

If low grade oils are being treated more chrome will be 
necessary, the amount being best judged by conducting the 
operation as usual and after the addition of the bichro- 
mate, removing a sample of the oil, washing the sample 
and noting the color of a rapidly cooled sample. 

A little practice will enable the operator to judge the 
correspondence between the color to be removed and the 
amount of bleaching mixture to be added. 

To obtain success with this process the method of work- 
ing given must be adhered to even in the smallest detail. 
This applies to the temperature at which each operation 
is carried out particularly. 

AIR BLEACHING OF PALM OIL. 

The method of conducting this process is identical with 
the chrome process to the point where the hydrochloric acid 
is to be added to the oil. In this method no acid or 
chrome is necessary, as the active bleaching agent is the 
oxygen of the air. 

The equipment is similar to that of the former process, 
except that a wooden tank in which no iron is exposed will 
suffice to bleach the oil in. The process depends in rapid- 
ity upon the amount of air blown through the oil and its 
even distribution. Iron should not be present or exposed 
to the oil during bleaching, as it retards the process con- 
siderably. 

After the impurities have been removed, as outlined 
under the chrome process, the temperature of the oil is 
raised by open steam to boiling. The steam is then shut 
off and air allowed to blow through the oil until it is com- 
pletely bleached, the temperature being maintained above 
150* F. by occasionally passing in steam. Usually a ton 
of oil is readily and completely bleached after the air has 

12 



RAW MATERIALS 

been passed through it for 18 to 20 hours, provided the 
oil is thoroughly agitated by a sufficient flow of air. 

If the the oil has been allowed to settle over night, it is 
advisable to run off the condensed water and impurities 
by the lower cock before agitating again the second day. 

When the oil has been bleached to the desired color, 
which can be determined by removing a sample and cool- 
ing, the mass is allowed to settle, the water run off to a 
waste tank from which any oil carried along may be 
skimmed off and the supernatant clear oil run to the stor- 
age or soap kettle. 

In bleaching by this process, while the process consumes 
more time and is not as efficient in bleaching the lower 
grade oils, the cost of bleaching is less and with a good 
oil success is more probable, as there is no possibility of 
any of the chrome liquors being present in the oil. These 
give the bleached oil a green tint when the chrome method 
is improperly conducted and they are not removed. 

Instead of blowing the- air through it, the heater oil may 
be brought into contact with the air, either by a paddle 
wheel arrangement, which, in constantly turning, brings 
the oil into contact with the air, or by pumping 
the heated oil into an elevated vessel, pierced with numer- 
ous fine holes from which the oil continously flows back 
into the vessel from which the oil is pumped. While in 
these methods air, light and heat act simultaneously in the 
bleaching of the oil, the equipment required is too cum- 
bersome to be practical. 

Recent investigations* in bleaching palm oil by oxygen 
have shown that not only the coloring matter but the oil 
itself was affected. In bleaching palm oil for 30 hours 
with air the free fatty acid content rose and titer decreased 
considerably. 

iSeifensieder Zeit, 1913, 40. p. 687, 724, 740. 

13 



SOAP-MAKING MANUAL 

Olive Oil, which comes from the fruit of the olive trees, 
varies greatly in quality, according to the method by which 
it is obtained and according to the tree bearing the fruit. 
Three hundred varieties are known in Italy alone. Since 
the larger portion of olive oil is used for edible purposes, 
a lower grade, denatured oil, denatured because of the 
tariff, is used for soap manufacture in this country. The 
oil varies in color from pale green to golden yellow. The 
percentage of free acid in this oil varies greatly, though the 
oil does not turn rancid easily. It is used mainly in the 
manufacture of white castile soap. 

Olive oil foots, which is the oil extracted by solvents after 
the better oil is expressed, finds its use in soap making 
mostly in textile soaps for washing and dyeing silks and 
in the production of green castile soaps. 

Other oils, as poppy seed oil, sesame oil, cottonseed oil, 
rape oil, peanut (arachis) oil, are used as adulterants for 
olive oil, also as substitutes in the manufacture of castile 
soap, since they are cheaper than olive oil. 

Cottonseed Oil is largely used in the manufacture of 
floating and laundry soaps. It may be used for toilet 
soaps where a white color is not desired, as yellow spots 
appear on a finished soap in which it has been used after 
having been in stock a short time. 

Corn Oil and Soya Bean Oil are also used to a slight ex- 
tent in the manufacture of toilet soaps, although the oils 
form a soap of very little body. Their soaps also spot 
yellow on aging. 

Com oil finds its greatest use in the manufacture of 
soap for washing automobiles. It is further employed for 
the manufacture of cheap liquid soaps. 

Fatty Acids are also used extensively in soap manufac- 
ture. While the soap manufacturer prefers to use a neutral 
oil or fat, since from these the by-product glycerine is 

14 



RAW MATERIALS 

obtained, circumstances arise where it is an advantage to 
use the free fatty acids. Red oil (oleic acid, elaine) and 
stearic acid are the two fatty acids most generally bought 
for soap making. In plants using the Twitchell process, 
which consists in splitting the neutral fats and oils into 
fatty acids and glycerine by dilute sulphuric acid and pro- 
ducing their final separation by the use of so-called aromatic 
sulphonic acids, these fatty acids consisting of a mixture of 
oleic, stearic, palmitic acids, etc., are used directly after 
having been purified by distillation, the glycerine being ob- 
tained from evaporating the wash water. 

Oleic acid (red oil) and stearic acid are obtained usual- 
ly by the saponification, of oils, fats and greases by acid, 
lime or water under pressure or Twitchelling. The 
fatty acids thus are freed from their combination with 
glycerine and solidify upon cooling, after which they are 
separated from the water and pressed at a higher or lower 
temperature. The oleic acid, being liquid at ordinary 
temperature, together with some stearic and palmitic acid, 
is thus pressed out. These latter acids are usually sepa- 
rated by distillation, combined with the press cake further 
purified and sold as stearic acid. 

The red oil, sometimes called saponified red oil, is often 
semi-soHd, resembling a soft tallow, due to the presence 
of stearic acid. The distilled oils are usually clear, vary- 
ing in color from light to a deep brown. Stearic acid, 
which reaches the trade in slab form, varies in quality 
from a soft brown, greasy, crumbly solid of unpleasant 
odor to a snow white, wax-like, hard, odorless mass. The 
quality of stearic acid is best judged by the melting point, 
since the presence of any oleic acid lowers this. The melt- 
ing point of the varieties used in soap manufacture usually 
ranges from 128** to 132® F. Red oil is used in the manu- 
facture of textile soaps, replacing olive oil foots soap for 

15 



SOAP-MAKING MANUAL 

this purpose, chlorophyll . being used to color the soap 
green. Stearic acid, being the hard firm fatty acid, may be 
used in small quantities to give a better grade of soap body 
and finish. In adding this substance it should always 
be done in the crutcher, as it will not mix in the kettle. 
It finds its largest use for soap, however, in the manu- 
facture of shaving soaps and shaving creams, since it 
produces the non-drying creamy lather so greatly desired 
for this purpose. Both red oil and stearic acid being fatty 
acids, readily unite with the alkali carbonates, carbon diox- 
ide being formed in the reaction and this method is ex- 
tensively used in the formation of soap from them. 

RANCIDITY OF OILS AND FATS. 

Rancidity in neutral oils and fats is one of the problems 
the soap manufacturer has to contend with. The mere 
saying that an oil is rancid is no indication of its being 
high in free acid. The two terms rancidity and acidity are 
usually allied. Formerly, the acidity of a fat was looked 
upon as the direct measure of its rancidity. This idea is 
still prevalent in practice and cannot be too often stated 
as incorrect. Fats and oils may be acid, or rancid, or acid 
and rancid. In an acid fat there has been a hydrolysis of 
the fat and it has developed a rather high percentage of 
free acid. A rancid fat is one in which have been de- 
veloped compounds of an odoriferous nature. . An acid and 
rancid fat is one in which both free acid and organic com- 
pounds of the well known disagreeable odors have been 
produced. 

It cannot be definitely stated just how this rancidity 
takes place, any more than just what are the chemical 
products causing rancidity. The only conclusion that one 
may draw is that the fats are first hydrolyzed or split up 
into glycerine and free fatty acids. This is followed by 
an oxidation of the products thus formed. 

16 



RAW MATERIALS 

Moisture, air, light, enzymes (organized ferments) and 
bacteria are all given as causes of rancidity. 

It seems very probable that the initial splitting of the 
fats is caused by enzymes, which are present in the seeds 
and fruits of the vegetable oils and tissue of animal fats, 
in the presence of moisture. Lewkowitsch strongly em- 
phasizes this point and he is substantiated in his idea by 
other authorities. Others hold that bacteria or micro- 
organisms are the cause of this hydrolysis, citing the fact 
that they have isolated various micro-organisms from 
various fats and oils. The acceptance of the bacterial ac- 
tion would explain the various methods of preservation of 
oils and fats by the use of antiseptic preparations. It can- 
not, however, be accepted as a certainty that bacteria cause 
the rancidity of fats. 

The action of enzymes is a more probable explanation. 

The hydrolysis of fats and oils is accelerated when they 
are allowed to remain for some time in the presence of 
organic non-fats. Thus, palm oil, lower grades of olive 
oil, and tallow, which has been in contact with the animal 
tissue for a long time, all contain other nitrogenous matter 
and exhibit a larger percentage of free fatty acid than the 
oils and fats not containing such impurities. 

Granting this initial splitting of the fat into free fatty 
acids and glycerine, this is not a sufficient explanation. The 
products thus formed must be acted upon by air and light. 
It is by the action of these agents that there is a further 
action upon the products, and from this oxidation we as- 
certain by taste and smell (chemical means are still unable 
to define rancidity) whether or not a fat is rancid. While 
some authorities have presumed to isolate some of these 
products causing rancidity, we can only assume the presence 
of the various possible compounds produced by the actior 

17 



^ 



SOAP-MAKING MANUAL 

of air and light which include oxy fatty acids, lactones, al- 
cohols, esters, aldehydes and other products. 

The soap manufacturer is interested in rancidity to the 
extent of the effect upon the finished soap. Rancid fats 
form darker soaps than fats in the neutral state, and very 
often carry with them the disagreeable odor of a rancid oil. 
Further, a rancid fat or oil is usually high in free acid. It 
is by no means true, however, that rancidity is a meas- 
ure for acidity, for as has already been pointed out, an 
oil may be rancid and not high in free acid. 

The percentage of free fatty acid is of even greater 
importance in the soap industry. The amount of glycerine 
yield is dependent upon the percentage of free fatty acid 
and is one of the criterions of a good fat or oil for soap 
stock. 

PREVENTION OF RANCIDITY. 

Since moisture, air, light and enzymes, produced by the 
presence of organic impurities, are necessary for the ran- 
cidity of a fat or oil, the methods of preventing rancidity 
are given. Complete dryness, complete purification of fats 
and oils and storage without access of air or light are de- 
sirable. Simple as these means may seem, they can only 
be approximated in practice. The most difficult problem is 
the removal of the last trace of moisture. Impurities may 
be lessened very often by the use of greater care. In stor- 
ing it is well to store in closed barrels or closed iron 
tanks away from light, as it has been observed that oils 
and fats in closed receptacles become rancid less rapidly 
than those in open ones, even though this method of stor- 
ing is only partially attained. Preservatives are also Used, 
but only in edible products, where their effectiveness is an 
open question. 

CHEMICAL CONSTANTS OF OILS AND FATS. 

Besides the various physical properties of oils and fats, 

18 



RAW MATERIALS 

such as color, specific gravity, melting point, solubility, etc., 
they may be distinguished chemically by a number of 
chemical constants. These are the iodine number, the acetyl 
value, saponification number, Reichert-Meissl number for 
volatile acids, Hehner number for insoluble acids. These 
constants, while they vary somewhat with any particular 
oil or fat, are more applicable to the edible products and 
are criterions where any adulteration of fat or oil is sus- 
pected. The methods of carrying out the analyses of oils 
and fats to obtain these constants are given in the various 
texts'" on oils and fats, and inasmuch as they are not of 
great importance to the soap industry they are merely men- 
tioned here. 

OIL HARDENING OR HYDROGEN ATI NG. 

It is very well known that oils and fats vary in con- 
sistency and hardness, depending upon the glycerides 
forming same. Olein, a combination of oleic acid and 
glycerine, as well as oleic acid itself largely forms the 
liquid portion of oils and fats. Oleic acid (QgHwOa) is an 
unsaturated acid and differs from stearic acid CmHmO,), 
the acid forming the hard firm portion of oils and fats, 
by containing two atoms of hydrogen less in the mole- 
cule. Theoretically it should be a simple matter to intro- 
duce two atoms of hydrogen into oleic acid or olein, and 
by this mere addition convert liquid oleic acid and olein 
into solid stearic acid and stearine. 

For years this was attempted and all attempts to apply 
the well known methods of reduction (addition of hydro- 
gen) in organic chemistry, such as treatment with tin 
and acid, sodium amalgam, etc, were unsuccessful. In 
recent years, however, it has been discovered that in the 
presence of a catalyzer, nickel in finely divided form 



•Official Methods, sec Bull. 107, A. O. A. C, U. S. Dept. Agricult 

19 



SOAP-MAKING MANUAL 

or the oxides of nickel are usually employed, the process 
of hydrogenating an oil is readily attained upon a prac- 
tical basis. 

The introduction of hardened oils has opened a new 
source of raw material for the soap manufacturer in 
that it is now possible to use oils in soap making which 
were formerly discarded because of their undesirable 
odors. Thus fish or train oils which had up to the time 
of oil hydrogenating resisted all attempts of being per- 
manently deodorized, can now be employed very satis- 
factorily for soap manufacture. A Japanese chemist, 
Tsujimoto* has shown that fish oils contain an unsatu- 
rated acid of the composition QsHasOz, for which he pro- 
posed the name clupanodonic acid. By the catalytic hard- 
ening of train oils this acid passes to stearic acid and the 
problem of deodorizing these oils is solved.' 

At first the introduction of hardened oils for soap 
manufacture met with numerous objections, due to the 
continual failures of obtaining a satisfactory product by 
the use of same. Various attempts have now shown that 
these oils, particularly hardened train oils, produce 
extraordinarily useful materials for soap making. These 
replace expensive tallow and other high melting oils. It 
is of course impossible to employ hardened oils alone, as 
a soap so hard would thus be obtained that it would 
be difficultly soluble in water and possess very little lather- 
ing quality. By the addition of 20-25% of tallow oil or 
some other oil forming a soft soap a very suitable soap 
for household use may be obtained. Ribot' discusses this 
matter fully. Hardened oils readily saponify, may be 



*Joum. Coll. of Engin. Tokyo Imper. Univ. (1906), p. 1. Abs. 
Chem. Revue f. d. Fett-u. Harr, Ind. 16, p. 84; 20, p. 8. 

» Meyerheim— Fort, der Chem., Physik. und Physik. Chem. (1913), 
8. 6, p. 293-307. 

■Scifs. Ztg. (1913), 40, p. 142. 

20 



RAW MATERIALS 

perfumed without any objections and do not impart any 
fishy odor to an article washed with same. Meyerheim* 
states that through the use of hydrogenated oils the hard- 
ness of soap is extraordinarily raised, so that soap made 
from hardened cottonseed oil is twelve times as hard as 
the soap made from ordinary cottonseed oil. This soap 
is also said to no longer spot yellow upon aging, and as 
a consequence of its hardness, is able to contain a con- 
siderably higher content of rosin through which lather- 
ing power and odor may be improved. Hardened oils 
can easily be used for toilet soap bases, provided they 
are not added in too great a percentage. 

The use of hardened oils is not yet general, but there 
is little doubt that the introduction of this process goes a 
long way toward solving the problem of cheaper soap 
material for the coap making industry. 

GREASE. 

Grease varies so greatly in composition and consistency 
that it can hardly be classed as a distinctive oil or fat. 
It is obtained from refuse, bones, hides, etc., and while 
it contains the same constituents as tallow, the olein con- 
tent is considerably greater, which causes it to be more 
liquid in composition. Grease differs in color from an 
off-white to a dark brown. The better qualities are em- 
ployed in the manufacture of laundry and chip soap, 
while the poorer qualities are only fit for the cheapest of 
soaps used in scrubbing floors and such purposes. There 
is usually found in grease a considerable amount of gluey 
matter, lime and water. The percentage of free fatty 
acid is generally high. 

The darker grades of grease are bleached before be- 
ing used. This is done by adding a small quantity of 
sodium nitrate to the melted grease and agitating, then 

* Loc. dt. 

21 



SOAP-MAKING MANUAL 

removing the excess saltpeter by decomposing with sul- 
phuric acid. A better method of refining, however, is by 
distillation. The chrome bleach is also applicable. 

ROSIN (colophony, YELLOW ROSIN, RESINA). 

Rosin is the residue which remains after the distil- 
lation of turpentine from the various species of pines. 
The chief source of supply is in the States of Georgia 
North and South Carolina. It is a transparent, amber 
colored hard pulverizable resin. The better grades are 
light in color and known as water white (w. w.) and 
window glass (w. g.). These are obtained from a tree 
which has been tapped for the first year. As the same 
trees are tapped from year to year, the product becomes 
deeper and darker in color until it becomes almost black. 

The constituents of rosin are chiefly (80-90%) abietic 
acid or its anhydride together with pinic and sylvic 
acids. Its specific gravity is 1.07-1.08, melting point 
about 152.5 C, and it is soluble in alcohol, ether, benzine, 
carbon disulfide, oils, alkalis and acetic acid. The main use 
of rosin, outside of the production of varnishes, is in the 
production of laundry soaps, although a slight percentage 
acts as a binder and fixative for perfumes in toilet soaps and 
adds to their detergent properties. Since it is mainly com- 
posed of acids, it readily unites with alkaline carbonates, 
though the saponification is not quite complete and the 
last portion must be completed through the use of caustic 
hydrates, unless an excess of 10% carbonate over the 
theoretical amount is used. A lye of 20** B. is best 
adapted to the saponification of rosin when caustic hydrates 
are employed for this purpose, since weak lyes cause 
frothing. While it is sometimes considered that rosin 
is an adulterant for soap, this is hardly justifiable, as it 
adds to the cleansing properties of soap. Soaps contain- 

22 



RAW MATERIALS 

ing rosin are of the well known yellowish color common 
to ordinary laundry soaps. The price of rosin has so 
risen in the last few years that it presents a problem of 
cost to the soap manufacturer considering the price at 
which laundry soaps are sold. 

ROSIN SAPONIFICATION. 

As has been stated, rosin may be saponified by the use 
of alkaline carbonates. On account of the possibility of 
the soap frothing over, the kettle in which the operation 
takes place should be set flush with the floor, which 
ought to be constructed of cement. The kettle itself is 
an open one with round bottom, equipped with an open 
steam coil and skimmer pipe, and the open portion is 
protected by a semi-circular rail. A powerful grid, hav- 
ing a 3-inch mesh, covers one-half of the kettle, the 
sharp edges protruding upwards. 

The staves from the rosin casks are removed at the 
edge of the kettle, the rosin placed on the grid and 
beaten through with a hammer to break it up into small 
pieces. 

To saponify a ton of rosin there are required 200 lbs. 
soda ash, 1,600 lbs. water and 100 lbs. salt. Half the 
water is run into the kettle, boiled, and then the soda ash 
and half the salt added. The rosin is now added through 
the grid and the mixture thoroughly boiled. As carbon 
dioxide is evolved by the reaction the boiling is con- 
tinued for one hour to remove any excess of this gas. A 
portion of the salt is gradually added to grain the soap 
well and to keep the mass in such condition as to favor 
the evolution of gas. The remainder of the water is 
added to close the soap and boiling continued for one 
or two hours longer. At this point the kettle must be 
carefully watched or it will boil over through the further 

23 



SOAP-MAKING MANUAL 

escape of carbon dioxide being hindered. The mass, 
being in a frothy condition, will rapidly settle by con- 
trolling the flow of steam. The remaining salt is then 
scattered in and the soap allowed to settle for two hours 
or longer. The lyes are then drained off the top. 
If the rosin soap is required for toilet soaps, it is 
grained a second time. The soap is now boiled with 
the water caused by the condensation of the steam, which 
changes it to a half grained soap suitable for pumping. 
A. soap thus made contains free soda ash 0.15% or less, 
free rosin about 15%. The mass is then pumped to the 
kettle containing the soap to which it is to be added at 
the proper stage. The time consumed in thus saponifying 
rosin is about five hours. 

NAPHTHENIC ACIDS. 

The naphtha or crude petroleum of the various prov- 
inces in Europe, as Russia, Galacia, Alsace and Rou- 
mania yield a series of bodies of acid character upon re- 
fining which are designated under the general name of 
naphthenic acids. These acids are retained in solution 
in the alkaline lyes during the distillation of the naphtha 
in the form of alkaline naphthenates. Upon adding di- 
lute sulphuric acid to these lyes the naphthenates are 
decomposed and the naphthenic acids float to the sur- 
face in an oily layer of characteristic disagreeable odor 
and varying from yellow to brown in color*. In Russia 
particularly large quantities of these acids are employed 
in the manufacture of soap. 

The soaps formed from naphthenic acids have recently 
been investigated' and found to resemble the soaps made 
from cocoanut oil and palm kernel oi!, in that they are 



' Les Matieres Graisses (1914), 7, 69, p. 3367. 
*Zeit. f. Angew. Chem. (1914), 27, 1, p. 2-4. 

24 



RAW MATERIALS 

difficult to salt out and dissociate very slightly with water, 
The latter property makes them valuable in textile in- 
dustries when a mild soap is required as a detergent, e. g., 
in the silk industry. These soaps also possess a high solvent 
power for mineral oils and emulsify very readily. The 
mean molecular weight of naphthenic acids themselves is 
very near that of the fatty acids contained in cocoanut 
oil, and like those of cocoanut oil a portion of the sepa- 
rated acids are volatile with steam. The iodine number 
indicates a small content of unsaturated acids. 

That naphthenic acids are a valuable soap material is 
now recognized, but except in Russia the soap is not 
manufactured to any extent at the present time. 

ALKALIS. 

The common alkali metals which enter into the for- 
mation of soap are sodium and potassium. The hy- 
droxides of these metals are usually used, except in the 
so called carbonate saponification of free fatty acids in 
which case sodium and potassium carbonate are used. A 
water solution of the caustic alkalis is known as lye, and 
it is as lyes of various strengths that they are added 
to oils and fats to form soap. The density or weight of 
a lye is considerably greater than that of water, depend- 
ing upon the amount of alkali dissolved, and its weight 
is usually determined by a hydrometer. This instrument is 
graduated by a standardized scale, and while all hydro- 
meters should read alike in a liquid of known specific 
gravity, this is generally not the case, so that it is advisable 
to check a new hydrometer for accurate work against one 
of known accuracy. In this country the Baume scale has 
been adopted, while in England a different graduation 
known as the Twaddle scale is used. The strength of a 
lye or any solution is determined by the distance the in- 

25 



SOAP-MAKING MANUAL 

strument sinks into the solution, and we speak of the 
strength of a solution as so many degrees Baume or Twad- 
dle which are read to the point where the meniscus of the 
lye comes on the graduated scale. Hydrometers are 
graduated differently for liquids of different weights. In 
the testing of lyes one which is graduated from 0** to 
50® B. is usually employed. 

Caustic soda is received by the consumer in iron 
drums weighing approximately 700 lbs. each. The vari- 
ous grades are designated as 60, 70, 74, 76 and 77%, 
These percentages refer to the percentage of sodium 
oxide (NaaO) in 100 parts of pure caustic soda formed 
by the combination of 77}^ parts of sodium oxide and 
2254 parts of water, 77yi% being chemically pure caustic 
soda. There are generally impurities present in com- 
mercial caustic soda. These consist of sodium carbonate, 
sodium chloride or common salt and sometimes lime. It 
is manufactured by treating sodium carbonate in an iron 
vessel with calcium hydroxide or slaked lime, or by elec- 
trolysis of common salt. The latter process has yet been 
unable to compete with the former in price. Formerly 
all the caustic soda used in soap making was imported, 
and it was only through the American manufacturer 
using a similar container to that used by foreign manu- 
facturers that they were able to introduce their product. 
This prejudice has now been entirely overcome and most 
of the caustic soda used in this country is manufactured 
here. 

CAUSTIC POTASH. 

The output of the salts containing potassium is con- 
trolled almost entirely by Germany. Formerly the chief 
source of supply of potassium compounds was from the 
burned ashes of plants, but about fifty years ago the in- 
exhaustible salt mines of Stassfurt, Germany, were dis- 

26 



RAW MATERIALS 

covered. The salt there mined contains, besides the 
chlorides and sulphates of sodium, magnesium, calcium 
and other salts, considerable quantities of potassium 
chloride, and the Stassfurt mines at present are prac- 
tically the entire source of all potassium compounds, in 
spite of the fact that other localities have been sought 
to produce these compounds on a commercial basis, espe- 
cially by the United States government. 

After separating the potassium chloride from the mag- 
nesium chloride and other substances found in Stassfurt 
salts the methods of manufacture of caustic potash are 
identical to those of caustic soda. In this case, however, 
domestic electrolytic caustic potash may be purchased 
cheaper than the imported product and it gives results 
equal to those obtained by the use of the imported article, 
opinions to the contrary among soap makers being many. 
Most of the caustic potash in the United States is manu- 
factured at Niagara Falls by the Niagara Alkali Co., 
and the Hooker Electrochemical Co., chlorine being ob- 
tained as a by-product. The latter concern employs the 
Townsend Cell, for the manufacture of electrolytic pot- 
ash, and are said to have a capacity for making 64 tons 
of alkali daily. 

Since the molecular weight of caustic potash (56) is 
greater than that of caustic soda (40) more potash is 
required to saponify a pound of fat. The resulting potash 
soap is correspondingly heavier than a soda soap. When 
salt is added to a potassium soap double decomposition 
occurs, the potassium soap being transformed to a so- 
dium soap and the potassium uniting with the chlorine to 
form potassium chloride. This was one of the earliest 
methods of making a hard soap, especially in Germany, 
where potash was derived from leeching ashes of burned 
wood and plants. 

27 



SOAP-MAKING MANUAL 

SODIUM CARBONATE (sODA ASH). 

While carbonate of soda is widely distributed in na- 
ture the source of supply is entirely dependent upon the 
manufactured product. Its uses are many, but it is espe- 
cially important to the soap industry in the so called car- 
bonate saponification of free fatty acids, as a constituent 
of soap powders, in the neutralization of glycerine lyes 
and as a filler for laundry soaps. 

The old French Le Blanc soda process, which consists 
in treating common salt with sulphuric acid and reducing 
the sodium sulphate (salt cake) thus formed with car- 
bon in the form of charcoal or coke to sodium sulphide, 
which when treated with calcium carbonate yields a mix- 
ture of calcium sulphide and sodium carbonate (black ash) 
from which the carbonate is dissolved by water, has been 
replaced by the more recent Solvay ammonia soda process. 
Even though there is a considerable loss of salt and the by- 
product calcium chloride produced by this process is only 
partially used up as a drying agent, and for refrigerating 
purposes, the Le Blanc process cannot compete with the 
Solvay process, so that the time is not far distant when 
the former will be considered a chemical curiosity. In 
the Solvay method of manufacture sodium chloride (com- 
mon salt) and ammonium bicarbonate are mixed in so- 
lution. Double decomposition occurs with the formation 
of ammonium chloride and sodium bicarbonate. The lat- 
ter salt is comparatively difficultly soluble in water and 
crystallizes out, the ammonium chloride remaining in so- 
lution. When the sodium bicarbonate is heated it yields 
sodium carbonate, carbon dioxide and water; the car- 
bon dioxide is passed into ammonia which is set free from 
the ammonium chloride obtained as above by treatment 
with lime (calcium oxide) calcium chloride being the by- 
product. 

23 



RAW MATERIALS 

Sal soda or washing soda is obtained by recrystallixing 
a solution of soda ash in water. Large crystals of sal 
soda containing but 37% sodium carbonate are formed. 

POTASSIUM CARBONATE. 

Potassium carbonate is not extensively used in the 
manufacture of soap. It may be used in the forming of 
soft soaps by uniting it with free fatly acids. The meth- 
ods of manufacture are the same as fcr sodium carbonate, 
although a much larger quantity of potassium carbonate 
than carbonate of soda is obtained from burned plant 
ashes. Purified potassium carbonate is known as pearl ash, 

ADDITIONAL MATERIAL USED IN SOAP MAKING. 

Water is indispensable to the soap manufacturer. In the 
soap factory hard water is often the cause of much trouble. 
Water, which is the best solvent known, in passing through 
.the crevices of rocks dissolves some of The constituents 
of these, and the water is known as hard. This hard- 
ness is of two kinds, temporary and permanent* Tem- 
porarily hard water is formed by water, which contains 
carbonic acid, dissolving a portion of calcium carbonate 
or carbonate of lime. Upon boiling, the carbonic acid is 
driven from the water and the carbonate, being insoluble 
in carbon dioxide free water, is deposited. This is the 
cause of boiler scale, and to check this a small amount of 
sal ammoniac may be added to the water, which con- 
verts the carbonate into soluble calcium chloride and 
volatile ammonium carbonate. Permanent hardness it 
caused by calcium sulphate which is soluble in 400 parts 
of water and cannot be removed by boiling. 

The presence of these salts in water form insoluble lime 
soaps which act as inert bodies as far as their value for 
the common use of soap is concerned. Where the per- 
centage of lime in water is large this should be removed. 

29 



SOAP-MAKING MANUAL 

A method generally used is to add about 5% of 20* B. 
sodium silicate to the hard water. This precipitates the 
lime and the water is then sufficiently pure to use. 

Salt, known as sodium chloride, is used to a large ex- 
tent in soap making for "salting out" the soap during 
saponification, as well as graining soaps. Soap ordinarily 
soluble in water is insoluble in a salt solution, use pf 
which is made by adding salt to the soap which goes 
into solution and throws any soap dissolved in the lyes 
out of solution. Salt may contain magnesium and cal- 
cium chlorides, which of course are undesirable in large 
amounts. The products on the market, however, are 
satisfactory, thus no detail is necessary. 

Filling materials used are sodium silicate, or water 
glass, talc, silex, pumice, starch, borax, tripoli, etc. 

Besides these other materials are used in the refining 
of the oils and fats, and glycerine recovery, such as 
Fuller's earth, bichromates of soda or potash, sulphate of 
alumina, sulphuric and hydrochloric acids and alcohol. 

A lengthy description of these substances is not given, 
as their modes of use are detailed elsewhere. 



30 



CHAPTER II 

Construction and Equipment of a Soap Plant 

No fixed plan for the construction and equipment 
of a soap plant can be given. The specifications for a 
soap factory to be erected or remodeled must suit the 
particular cases. Very often a building which was con- 
structed for a purpose other than soap manufacture must 
be adapted for the production of soap. In either case 
it is a question of engineering and architecture, together 
with the knowledge obtained in practice and the final de- 
cision as to the arrangement is best solved by a confer- 
ence with those skilled in each of these branches. 

An ideal soap plant is one in which the process of soap 
making, from the melting out of the stock to the packing 
and shipping of the finished product, moves downward 
from floor to floor, since by this method it is possible to 
utilize gravitation rather than pumping liquid fats and 
fluid soaps. Convenience and economy are obtained by 
such an arrangement. 

The various machinery and other equipment for soap 
manufacture are well known to those connected with this 
industry. It varies, of course, depending upon the kind 
of soap to be manufactured, and full descriptions of the 
necessary machinery are best given in the catalogs issued 
by the manufacturers of such equipment, who in this 
country are most reliable. 

To know just what equipment is necessary can very 
easily be described by a brief outline of the process vari- 
ous soaps undergo to produce the finished article. After 
the saponification has taken place in the soap kettle the 
molten sdStp is run directly into the soap frames, 

31 



SOAP-MAKING MANUAL 

which consist of an oblong compartment, holding any- 
where from 400 to 1,200 pounds, with removable steel 
sides and mounted upon trucks, in which it solidifies. In 
most cases it is advisable to first run the soap into a 
crutcher or mixer which produces a more homogeneous 
mass than if this operation is omitted. Color and per- 
fume may also be added at this point, although when a 
better grade of perfume is added it must be remembered 
that there is considerable loss due to volatilization of 
same. When a drying machine is employed the molten 
soap is nm directly upon the rollers of this machine, 
later adding about 1.0% zinc oxide to the soap from 
which it passes continuously through the drying chamber 
and is emitted in chip form ready for milling. After 
the soap has been framed, it is allowed to cool and 
solidify, which takes several days, and then the sides of 
the frame are stripped off. The large solid cake is cut with 
wires by hand or by a slabber into slabs of any desired 
size. These slabs are further divided into smaller di- 
visions by the cutting table. In non-milled soaps (laun- 
dry soaps, floating soaps, etc.), these are pressed at this 
stage, usually by automatic presses, after a thin hard 
film has been formed over the cake by allowing it to dry 
slightly. In making these soaps they are not touched by 
hand at any time during the operation, the pressing, 
wrapping and packing all being done by machinery. For 
a milled soap the large slabs are cut into narrow oblong 
shapes by means of the cutting table to readily pass into 
the feeder of the chipper, the chips being spread upon 
trays and dried in a dry house until the moisture content 
is approximately 15%. 

The process of milling is accomplished by passing the 
dried soap chips through a soap mill, which is a machine 
consisting of usually three or four contiguous, smooth, 

32 



CONSTRUCTION AND EQUIPMENT 

granite rollers operated by a system of gears and set 
far enough apart to allow the soap to pass from a hopper 
to the first roller, from which it is constantly conveyed 
to each succeeding roller as a thin film, and finally 
scraped from the last roller to fall into the milling box 
in thin ribbon form. These mills are often operated in 
tandem, which necessitates less handling of soap by the 
operator. The object of milling is to give the soap a 
glossy, smooth finish and to blend it into a homogeneous 
mass. The perfume, color, medication or any other ma- 
terial desired are added to the dried soap chips prior to 
milling. Some manufacturers use an amalgamator to 
distribute these uniformly through the soap, which elimi- 
nates at least one milling. When a white soap is being 
put through the mill, it is advisable to add from 
0.5% to 1% of a good, fine quality of zinc oxide to the 
soap, if this substance has not been previously added. 
This serves to remove the yellowish cast and any trans- 
lucency occasioned by plodding. Too great a quantity 
of this compound added, later exhibits itself by imparting 
to the soap a dead white appearance. Inasmuch as the 
milling process is one upon which the appearance of a 
finished cake of toilet soap largely depends, it should be 
carefully done. The number of times a soap should be 
milled depends upon the character of a soap being worked. 
It should of course be the object to mill with as high a 
percentage of moisture as possible. Should the soap be- 
come too dry it is advisable to add water directly, rather 
than wet soap, since water can more easily be distributed 
through the mass. As a general statement it may be said 
it is better policy to overmill a soap, rather than not mill 
it often enough. 

After the soap has been thoroughly milled it is read^* 
for plodding. A plodder is so constructed as to take f 

33 



SOAP-MAKING MANUAL 

soap ribbons fed into the hopper by means of a worm screw 
and continuously force it under great pressure through a 
jacketed cylinder through which cold water circulates in 
the rear to compensate the heat produced by friction and 
hot water at the front, to soften and polish the soap which 
passes out in solid form in bars of any shape and size 
depending upon the form of the shaping plate through 
which it is emitted. The bars run upon a roller board, 
are cut into the required length by a special cake cutting 
table, allowed to dry slightly and pressed either auto- 
matically or by a foot power press in any suitable soap die. 
The finished cake is then ready for wrapping and after due 
time in stock reaches the consumer. 

Besides the various apparatus mentioned above there are 
many other parts for the full equipment of a modern soap 
plant, such as remelters, pumps, mixers, special tanks, 
power equipment, etc. As has been stated, however, prac- 
tical experience will aid in judging the practicability as to 
installation of these. The various methods of powdering 
soap are, however, not generally known. Where a coarse 
powder is to be produced, such as is used for common 
washing powders, no great difficulty is experienced with 
the well known Blanchard mill. In grinding soap to an 
impalpable powder the difficulties increase. The methods 
adapted in pulverizing soaps are by means of disinte- 
grators, pebble mills and chaser mills. The disintegrator 
grinds by the principle of attrition, that is, the material is 
reduced by the particles being caused to beat against each 
other at great velocity; a pebble mill crushes the sub- 
stance by rubbing it between hard pebbles in a slowly re- 
volving cylinder; the chaser mill first grinds the material 
and then floats it as a very fine powder above a curb of 
fixed height. The last method is particularly adapted for 
the finest of powder (140 mesh and over). 

34 



CHAPTER III 

Classification of Soap-Making Methods. 

In the saponification of fats and oils to form soap 
through the agency of caustic alkalis, as has been stated, 
the sodium or potassium salts of the mixed fatty acids are 
formed. Sodium soaps are usually termed hard soaps, and 
potassium soaps soft. There are, however, a great many 
varieties of soaps the appearance and properties of which 
depend upon their method of manufacture and the oils or 
fats used therein. 

The various methods adopted in soap making may be 
thus classified: 

1. Boiling the fats and oils in open kettles by open 
steam with indefinite quantities of caustic alkali solutions 
until the finished soap is obtained; ordinarily named full 
boiled soaps. These may be sub-divided into (a) hard 
soaps with sodium hydrate as a base, in which the glycerine 
is recovered from the spent lyes; (b) hard soaps with 
soda as a base, in which the glycerine remains in the 
soap, e. g., marine cocoanut oil soaps; (c) soft potash 
soaps, in which the glycerine is retained by the soap. 

2. Combining the required amount of lye for complete 
saponification of a fat therewith, heating slightly with dry 
heat and then allowing the saponification to complete itself. 
This is known as the cold process. 

3. Utilizing the fatty acid, instead of the neutral fat, 
and combining it directly with caustic alkali or carbonate, 
which is incorrectly termed carbonate saponiHcationt since 
it is merely neutralizing the free fatty acid and thus is 
not a saponification in the true sense of the word. No 
glycerine is directly obtained by this method, as it 

35 



SOAP-MAKING MANUAL 

usually previously removed in the clearage of the fat by 
either the Twitchell or autoclave saponification method. 

In the methods thus outlined the one most generally 
employed is the full boiled process to form a sodium soap. 
This method of making soap requires close attention and 
a knowledge which can only be obtained by constant prac- 
tice. The stock, strength of lyes, heat, amount of salt or 
brine added« time of settling, etc., are all influencing 
factors. 

The principles involved in this process are briefly these: 

The fat is partly saponified with weak lyes (usually 
those obtained from a previous boiling in the strengthening 
change are used), and salt is added to grain the soap. The 
mass is then allowed to settle into two layers. The upper 
layer is partly saponified fat; the lower layer, or spent lye, 
is a solution of salt, glycerine, and contains any albuminous 
matter or any other impurity contained in the fat. This 
is known as the killing or glycerine change. Strong lyes 
are now added and the fat entirely saponified, which is 
termed the strengthening change. The mass is then al- 
lowed to settle and the fluid soap run off above the "nigre." 
This operation is called the finish or finishing change. 

The method may be more fully illustrated by a concrete 
example of the method of manufacture of a tallow base: 

Charge — 

Tallow 88 per cent. 

Cocoanut oil 10 per cent. 

Rosin w. w 2 per cent. 

Amount charge 10 tons 

About five tons of tallow and one ton of cocoanut oil 
are pumped or run into the soap kettle and brought to a 
^oil with wet steam until it briskly comes through the hot 

•. The caustic soda (strengthening lyes from former 

36 



SOAP-MAKING METHODS 

boilings may be used here) is gradually added by the dis- 
tributing pipe, any tendency to thicken being checked by 
the introduction of small quantities of brine ("salt pickle"). 
If the lye is added too rapidly the soap assumes a granular 
^pearance, indicating that the addition of same must be 
discontinued. Water should then be added and the mass 
boiled through until it again closes. When the addition 
of the proper amount of caustic soda is nearing its com- 
pletion the soap gradually thins. The steam is now cut 
down to about one turn of the valve, and brine is rapidly 
added or salt shoveled in. In ten to fifteen minutes the 
steam again breaks through and, from the appearance of 
the soap, it can be seen whether sufficient brine has been 
added. A sample taken out by means of a long wooden 
paddle should show the soap in fine grains with the lyes 
running from it clear. The steam is then shut off and the 
soap allowed to settle from one and one-half to two hours. 
In all settlings the longer time this operation is permitted 
to continue, the better will the subsequent operations 
proceed. 

The mixture now consists of a partly saponified layer 
of fat above the spent lyes. The lyes are drawn off until 
soap makes its appearance at the exit pipe. The valve is 
then closed and the soap blown back into the kettle by 
steam. The lyes thus obtained are known as spent lyes, 
from which the glycerine is recovered. They should show 
an alkalinity of approximately 0.5 per cent, if the operation 
is carefully carried out. 

The remaining tallow is now added and the above oper- 
ations repeated. 

After the spent lyes have been drawn off, the soap is 
closed with water and the proper percentage of rosin soap 
previously formed, or rosin itself is added to the mass in 
the kettle More lye is then allowed to flow in until the 

37 



SOAP-MAKING MANUAL 

mixture is up to 'Wength/' This is usually tested by the 
"bite" on the tongue of a small cooled sample. After boil 
ing until the steam comes through, the mass is grained with 
salt as before and allowed to settle one and one-half to 
three hours. These lyes, known as strengthening lyes, 
are run to storage to be used subsequently with fresh fat 
to take up the caustic soda contained therein. 

The soap is now ready for finishing and is first boiled 
through and tried for strength. A drop of phenolphthalein 
(1 per cent, phenolphthalein in 98 per cent, alcohol) is al- 
lowed to drop on the molten soap taken up on a trowel. 
The red color should be instantly produced and develop to 
a full deep crimson in a few seconds, or more lye must be 
added until this condition is realized. Should it flash a 
deep crimson immediately it is on the strong side. This 
cannot be conveniently remedied; it can only serve as a 
guide for the next boil, but in any case it is not of any 
serious consequence, unless it is too strong. 

With the steam on, the soap is now examined with a 
trowel which must be thoroughly heated by working it 
about under the surface of the hot soap. The appearance 
of the soap as it runs from the face of the trowel indicates 
its condition. It is not possible to absolutely describe the 
effect, which can only be properly judged by practice, yet 
the following points may serve as a guide. The indications 
to be noticed are the shape and size of the flakes of soap 
as the sample on the trowel breaks up and runs from the 
hot iron surface, when the latter is turned in a vertical 
position, as well as the condition of the iron surface from 
which the soap flakes have fallen. A closed soap will run 
slowly into a homogeneous sheet, leaving the trowel's sur- 
face covered with a thin layer of transparent soap; a 
grained mass will run rapidly down in tiny grains, about 
one-half an inch in diameter or less, leaving the hot trowel 

38 



SOAP-MAKING METHODS 

absolutely dry. The object of the finish is to separate the 
soaps of the lower fatty acids from those of the higher, and 
both from excess of liquid. A point midway between 
**open** and "closed" is required to arrive at this point 

Having arrived at the above condition, the soap is al- 
lowed to settle anywhere from one to three days and tlien 
run off through the skimmer pipes to the nign^e and framed 
or pumped to the tank feeding the drying machine. 

The stock thus obtained should be fairly white, depend- 
ing upon the grade of tallow used and slightly alkaline to 
an alcoholic phenolphthalein solution. If removed at ex- 
actly the neutral point or with a content of free fat the 
soap will sooner or later develop rancidity. The soap thus 
obtained is an ordinary tallow base, and the one by far 
greatest used in the manufacture of toilet soaps. The per- 
centage of cocoanut oil indicated is not fixed and may 
readily be varied, while in fine toilet soap the rosin is 
usually eliminated. 

In the manufacture of full boiled soda soaps in which no 
glycerine is obtained as a by-product, it being retained in 
the soap itself, the soap formed is known as a "run" soap. 
The process is used most extensively in the manufacture 
of marine soaps by which the method may be best illus- 
trated. This soap is known as marine soap because of its 
property of readily forming a lather with salt water and 
is mostly consumed aboard vessels. 

Marine soaps are manufactured by first placing in the 
kettle a calculated amount of lye of 25 deg. to 35 deg. B., 
depending upon the amount of moisture desired in the fin- 
ished soaps, plus a slight excess required to saponify a 
known weight of cocoanut oil. With open steam on, the 
cocoanut oil is then gradually added, care being taken that 
the soap does not froth over. Saponification takes place 
readily and when the oil is entirely saponified the finished 

39 



SOAP-MAKING MANUAL 

soap is put through the process known as running. This 
consists in constantly pumping the mass from the skimmer 
pipe back into the top of the kettle, the object being to 
prevent any settling of the nigre or lye from the soap, as 
well as producing a homogeneous mass. It is customary 
to begin the saponification in the morning, which should be 
completed by noon. The soap is then run for about three 
hours and framed the next morning. After having re- 
mained in the frame the time required to solidify and cool, 
the soap is slabbed and cut into cakes. This process is 
difficult to carry out properly, and one not greatly em- 
ployed, although large quantities of marine soap are pur- 
chased by the government for use in the navy and must 
fulfill certain specifications required by the purchasing 
department. 

In making potash soaps it is practically impossible to ob- 
tain any glycerine directly because of the pasty consistency 
of the soap, and no graining is possible because the addi- 
tion of salt to a soft soap, as already explained, would form 
a soda soap. Large quantities of soft soaps are required for 
the textile industries who desire mostly a strong potash 
soap, and the large number of automobiles in use at the 
present time has opened a field for the use of a soft soap 
for washing these. A soap for this purpose must be neu- 
tral so as not to affect the varnish or paint of automobiles. 

A suitable soap for textile purposes may be made as 
follows : 

Red oil 80 parts 

House grease 20 parts 

Caustic soda lye, 36 degs. B . . . . 3 parts 

Carbonate of potash 5^4 parts 

Caustic potash 23^ parts 

Olive oil, com oil, soya bean oil, olive oil foots or cot- 

4$ 



SOAP-MAKING METHODS 

tonseed oil may replace any of the above oils. A large 
quantity of cottonseed oil will cause the soap to fig. 

To carry out the process, the caustic potash and car- 
bonate of potash are dissolved and placed in the kettle 
together with the soda lye, and the oils added. This is 
most satisfactorily accomplished by being finished the day 
before the boiling is begun. The next day the boiling is 
begun and water added to bring the soap up to the desircii 
percentage of fatty acid, due allowance being made for the 
water formed by the condensation of the open steam in 
boiling. Care must be taken that the soap in the kettle 
does not swell and run over during the saponification. 
A good procedure is to use open steam for a period of 
about two hours, then close the valve and allow the sapon- 
ification to continue without boiling, and repeat this until 
it is entirely saponified. After the saponification has been 
completed the soap is briskly boiled all day and the proper 
corrections made ; that is, if too alkaline, more oil is added, 
and if free fat is present, more potash. About 2 pet cent, 
carbonate of potash is the proper amount for a soap con- 

( taining 50 per cent, fatty acid. The soap is sampled by 

allowing it to drop on a clean, cold glass surface. In so 

^ doing, the soap should not slide or slip over the glass sur- 

face when pressed thereon, but should adhere to the glass, 
or it is too alkaline. A sample worked between the fingers 
showing too much stringiness should have more strong 
potash and oil added. A sample taken out in a pail and 
allowed to cool over night will serve as a guide as to the 
body of the soap in the kettle. When the soap has thus 
been properly finished it is run into barrels. 

For an automobile soap the following is a good working 
formula : 

Corn oil....! 1,000 parts 

Potash lye, SVA degs. B 697 parts 

41 



SOAP-MAKING MANUAL 

Proceed as in the directions just given for textile soap 
in placing charge in the kettle. When the kettle is boiling 
up well, shut off the steam and the saponification will com- 
plete itself. The soap may be run into the barrels the 
next day. 

A heavy soap with a smaller percentage of fat may be 
made as follows: 

Corn oil l^OOOparts 

Potash lye, 24^4 degs. B 900 parts 

Boil until the soap bunches, and shovel the finished soap 
into barrels. Upon standing it will clear up. By the addi- 
tion of more water the yield of soap per pound of oil may 
be run up to 300 per cent. 

After soft soaps have been allowed to stand for some 
time the phenomenon known as "figging" often occurs. 
This term is applied to a crystalline-like formation, caus- 
ing spots of a star-like shape throughout the soap. 
This is undoubtedly due to the stearine content of the soap 
crystallizing out as it cools, and forming these peculiarly- 
shaped spots. It more generally occurs in the winter and 
may be produced artificially by adding a small quantity ot 
soda to the potash lye before saponification. 

The oils usually employed in the manufacture of potash 
soaps are cottonseed oil, corn oil, soya bean oil, olive oil 
foots, red oil, cocoanut oil, grease and the various train 
oils. The usual percentage yield is from 225 per cent, to 
300 per cent., based upon the weight of oil used. In cal- 
culating the weight of a soft soap it is to be remembered 
that since potassium has a higher molecular weight (56) 
than sodium (40), the corresponding soap formed is that 
much greater in weight when compared with a sodium 
soap. Rosin may be added to soft soaps as a cheapening 
agent. 

42 



SOAP-MAKING METHODS 

> COLD PROCESS. 

The cold process for manufacturing soap is the simplest 
method of soap making, and the equipment required is small 
when compared to the other methods. All the more expensive 
equipment that is necessary is a crutcher, a tank to hold the 
lye, frames, a slabber or cutting table, and a press. Yet, 
in spite of the simplicity of thus making soap, the disad- 
vantages are numerous for the production of a good piece 
of soap. The greatest difficulty is to obtain a thorough 
combination of oil or fat and lye so that there will not be 
an excess of one or the other in the finished soap. At its 
best there is either a considerable excess of free fat which 
later exhibits itself in producing rancidity or uncombined 
caustic, which produces an unpleasant effect on the skin 
when the soap is consumed for washing. The latter ob- 
jection, of course, can only be applied to toilet soaps. 

Cocoanut oil is used very largely in the manufacture of 
cold-made soaps as it is well adapted for this purpose, al- 
though it is by no means true that other oils may 'not be 
employed. Since by this process of manufacture no im- 
purity contained in the fat or oil is removed in the making 
of the soap, it is necessary that in order to obtain a fine 
finished product, any impurity contained in these may be 
removed if present, or that the fats be as pure as can be 
obtained. If inedible tallow is used for cold-made soap, 
it is advisable to bleach it by the Fuller's Earth Process. 

The carrying out of this method is best illustrated by 
an example of a cold-made cocoanut oil soap. 

Charge : 

Cochin cocoanut oil 846 parts 

Lye (soda), 35 degs. B 470 parts 

Water 24 parts 

43 



SOAP-MAKING MANUAL 

The oil is run into the crutchcr and the temperature of 
the oil raised to 100 degs. F. by dry steam. The lye and 
water are at room temperature. After all the oil is in the 
crutcher, the lye and water are slowly added to prevent 
any graining of the soap. Toward the end the lye may be 
added more rapidly. When all the lye is in, the mass is 
crutched for about three hours, or until upon stopping 
the crutcher a finger drawn over the surface of the soap 
leaves an impression. If this condition is not realized, 
the soap must be mixed until such is the case. Having ar- 
rived at this point, the mixture is dropped into a frame 
which should remain uncovered. The heat produced by the 
further spontaneous saponification will cause the soap to 
rise in the middle of the frame. After having set for some 
days it is ready to be slabbed and cut into cakes. 

A potash soap may be made by the cold process just as 
readily as a soda soap. Soaps of this type may be made 
by either of these formulae in a crutcher: 

Olive oil foots 600 

Potash lye, 18 degs. B. hot, 20 degs. B. cold . . 660 
or 

Corn oil 800 

Rosin 200 

Potash lye, 27 degs. B 790 

Water 340 

Heat the oils to 190 degs. F., add the lye and crutch 
until the soap begins to bunch, when it is ready to be run 
into barrels where the saponification will be completed. 

Semi-boiled soaps differ from those made by the cold 
process in temperature. In making semi-boiled soaps the 
fats are usually heated to 140° F. The addition of the 

44 



SOAP-MAKING METHODS 

lye raises the temperature to 180* — ^200** F. when saponifi- 
cation takes place. 

CARBONATE SAPONIFICATION. 

The method of the formation of soap by the utilization 
of the fatty acid directly, from which the glycerine has al- 
ready been removed by some method of saponification 
other than with caustic soda, and neutralizing this with 
alkali, is becoming increasingly popular. The glycerine is 
more easily recovered from a previous cleavage of the 
fats or oils, but a soap made from the mixed fatty acids 
thus obtained is seldom white in color and retains an un- 
pleasant odor. Since soda ash or sodium carbonate is 
cheaper than caustic soda and readily unites with a fatty 
acid, it is used as the alkali in the carbonate saponification. 
The process is similar to that already given under Rosin 
Saponification. About 19 per cent, by weight of the fatty 
acids employed of 58 per cent, soda ash is dissolved in 
water until it has a density of 30 degs. B., and the solu- 
tion is run into the kettle, which is usually equipped with a 
removable agitator. The fatty acids, previously melted, are 
then slowly added while the mixture is boiled with open 
steam and agitated with the stirring device. The fatty 
acids instantly unite with the carbonate and rise in the 
kettle, due to the generation of carbon dioxide, and care 
must be exercised to prevent boiling over. After all the 
fatty acid has been added, and the mass is boiled through 
the saponification must be completed with caustic soda, as 
there is as yet no practical method known which will 
split a fat entirely into fatty acid and glycerine. Thus 
about 10 per cent, of the fatty acids are true neutral fats 
and require caustic soda for their saponification. This is 
then added and the soap completed, as in full-boiled soaps. 

In carrying out this method upon a large scale, large 

45 



SOAP-MAKING MANUAL 

quantities of carbon dioxide are formed during the boiling 
of the soap, which replaces a quantity of the air contained 
therein. The kettle room should therefore be well venti- 
lated, allowing for a large inflow of fresh air from out 
of doors. 



46 



CHAPTER IV 

Classification of Soaps. 

In considering the many different varieties of soaps, 
their classification is purely an arbitrary one. No definite 
plan can be outlined for any particular brand to be manu- 
factured nor can any very sharp distinction be drawn be- 
tween the many soaps of different properties which are 
designated by various names. It is really a question to 
what use a soap is to be put, and at what price it may 
be sold. There is, of course, a difference in the appear- 
ance, form and color, and then there are soaps of special 
kinds, such as floating soaps, transparent soaps, liquid 
soaps, etc., yet in the ultimate sense they are closely allied, 
because they are all the same chemical compound, 
varying only in their being a potash or soda soap, and in 
the fatty acids which enter into combination with these 
alkalis. Thus we can take a combination of tallow 
and cocoanut oil and make a great many presumably dif- 
ferent soaps by combining these substances with caustic 
soda, by different methods of manufacture and by incor- 
porating various other ingredients, as air, to form a float- 
ing soap, alcohol to make a transparent soap, dyestuffs to 
give a different color, etc., but essentially it is the same 
definite compound. 

The manufacturer can best judge the brand of soaps he 
desires to manufacture, and much of his success depends 
upon the name, package, shape, color or perfume of a 
cake of soap. It is the consumer whom he must please 
and many of the large selling brands upon the market 
today owe their success to the above mentioned details. 
The great majority of consumers of soap know very little 

47 



SOAP-MAKING MANUAL 

concerning soap, except the fact that it washes or has a 
pleasant odor or looks pretty, and the manufacturer of 
soap must study these phases of the subject even more 
carefully than the making of the soap itself. 

For a matter of convenience we will classify soap under 
three general divisions: 

I. Laundry soaps, including chip soaps, soap powders 
and scouring soaps. 

II. Toilet soaps, including floating soap, castile soap, 
liquid soap, shaving soap, etc. 

III. Textile soaps. 

LAUNDRY SOAP. 

The most popular household soap is laundry soap. A 
tremendous amount of this soap is consumed each day in 
this country, and it is by far manufactured in larger quan- 
tities than any other soap. It is also a soap which must 
be sold cheaper than any otlier soap that enters the 
home. 

The consumers of laundry soap have been educated to 
use a full boiled settled rosin soap and to make a good 
article at a price this method should be carried out, as it is 
the one most advisable to use. The composition of the fats 
entering into the soap depends upon the market price of 
these, and it is not advisable to keep to one formula in the 
manufacture of laundry soap, but rather to adjust the 
various fatty ingredients to obtain the desired results with 
the cheapest material that can be purchased. It is impos- 
sible to use a good grade of fats and make a profit upon 
laundry soap at the price at which it must be retailed. The 
manufacturer of this grade of soap must look to the by- 
product, glycerine, for his profit and he is fortunate indeed 
if he realizes the entire benefit of this and still produces 
a superior piece of laundry soap. 

48 



CLASSIFICATION OF SOAPS 

SEMI-BOILED LAUNDRY SOAPS, 

It is advantageoas at times to make a laundry soap by 
a method other than the full boiled settled soap pro- 
cedure as previously outlined. This is especially the con* 
dition in making a naphtha soap, in which is incorporated 
naphtha, which is very volatile and some of the well known 
manufacturers of this class of soap have adopted this 
process entirely. A laundry soap containing rosin cannot 
be advantageously made by the cold process, as the soap 
thus made grains during saponification and drops a por- 
tion of the lye and filling materials. By making a semi- 
boiled soap this objection is overcome. The half boiled 
process differs from the cold process by uniting the fats 
and alkalis at a higher temperature. 

To carry out this process the following formulae have 
been found by experience to give satisfactory results. 

I. lbs. 

Tallow 100 

Rosin 60 

Soda Lye, 36'' B 80 

II. 

Tallow 100 

Rosin 60 

Silicate of Soda 25 

Soda Lye, 36^ B 85 

III. 

Tallow 100 

Rosin 100 

Lye, 36** B 105 

Silicate of Soda 25 

Sal Soda Solution 20 

49 



SOAP-MAKING MANUAL 

In any of these formulas the sodium silicate (40** B.) 
may be increased to the same proportion as the fats used. 
By so doing, however, twenty pounds of 36" B. lye must 
he added for every hundred pounds of silicate additional 
to that indicated or in other words, for every pound of 
silicate added 20 per cent, by weight of 36" B. lye must 
be put into the mixture. The rosin may also be replaced 
by a previously made rosin soap. 

To make a semi-boiled soap, using any of the above 
formulae, first melt the rosin with all or part of the fat, 
as rosin when melted alone readily decomposes. When 
the mixture is at 150° F. run it into the crutcher and add 
the lye. Turn on sufficient dry steam to keep the tempera- 
ture of the soap at about 150" F. in the winter or 130" F. 
in summer. After the mass has been mixed for half an 
hour, by continuously crutching the soap it will at first 
thicken, then grain and it may again become thick before 
it becomes smooth. When the mass is perfectly smooth 
and homogeneous drop into a frame and crutch in the 
frame by hand to prevent streaking. After standing the 
required length of time the soap is finished into cakes as 
usual. 

SETTLED ROSIN SOAP. 

Settled rosin soaps are made from tallow, grease, cotton- 
seed oil, bleached palm oils of the lower grades, corn oil, 
soya bean oil, arachis oil, distilled garbage grease, cotton 
seed foots or fatty acids together with an addition of rosin, 
varying from 24 per cent, to 60 per cent, of the fatty acids 
which should titer from 28 to 35. A titer lower than 28 
will prevent the finished kettle of soap from being capable 
of later taking up the filling materials. As has already 
been stated under hardened oils, these being very much 
higher in titer allow a greater percentage of rosin to be 
added. Thus hardened fish oils and cottonseed oil are 

50 



^M 



CLASSIFICATION OF SOAPS 

gradually being more extensively employed in soaps of this 
character. 

The procedure of handling the kettle is similar to that 
given under full boiled soap. The stock is steamed out 
into a settling tank and allowed to settle over night, after 
which it is pumped into the soap kettle. Having stocked the 
kettle, open steam is turned on and 10''-12** B. lye is run in, 
while using a steam pressure of ninety to one hundred 
pounds in order to prevent too great a quantity of conden- 
sation of the steam, the water thus being formed weaken- 
ing the lye. If a steam pressure of fifty to sixty pounds is 
available, a stronger lye (20" B.) should be added. Care 
must be taken not to allow the lye to flow in too rapidly 
or the soap will not grain. The saponification is only at- 
tained by prolonged boiling with sufficient lye of proper 
strength. When saponification has taken place, the mass 
begins to clear and a sample taken out with a paddle and 
cooled should show a slight pink with a 1 per cent, alcoholic 
phenolphthalein solution. 

It may be stated here that in using this indicator or any 
other to test the alkalinity of soap, the soap should always 
be cooled and firm, as whenever water is present, the disso- 
ciation of the soap thereby will always react alkaline. When 
this state is reached the mass is ready for graining, which 
is accomplished by distributing salt brine or pickle or 
spreading dry salt over the surface of the soap. The 
kettle is then thoroughly boiled until the mass shows a 
soft curd and the lye drops clearly from a sample taken 
out with a trowel or paddle. The steam is then shut off 
and the soap allowed to settle over night. The lyes are 
then run off to the spent lye tank for glycerine recovery. 
In saponifying a freshly stocked kettle it is apt to bunch. 
To prevent this salt is added at various times to ap- 
proximately one per cent, of the fat used. 

51 



SOAP-MAKING MANUAL 

If, by any possibility the soap has bunched, this condition 
may be remedied by the addition of more strong lye and 
boiling until it is taken up. To work a kettle to its full 
capacity it is advisable to make two "killing" changes. 
First add about 75 per cent, of the fat and grain as directed. 
Run off the spent lyes and then add the remainder of the 
stock and repeat the process. When the spent lye has been 
run to storage, the open steam is again turned on and 
18" B lye gradually allowed to run in. The rosin is now 
broken up and put into the kettle, or a previously made 
rosin soap is pumped in. 

Lye is then added until the soap has a sharp taste after 
about three hours of continous boiling, or when the soap 
is in the closed state. More lye should then be run into 
the kettle to grain the soap well, the grain not being too 
small. Then allow the soap to settle over night and draw 
off the strengthening lye. The next day again boil up 
the kettle and add water until the soap thins out and rises 
or swells high in the kettle. A sample taken out at this 
stage upon a hot trowel should run off in large flakes. 
The surface of the soap should be bright and shiny. 

If the sample clings to the trowel, a slight addition of 
lye will remedy this defect. The kettle is then allowed to 
rest, to drop the nigre and to cool for some time, depending 
upon the size of the kettle. The proper temperature is 
such that after having been pumped to the crutcher and the 
filling materials having been added, a thermometer placed 
into the mass should indicate 128°-135*' F. after the crutcher 
has run from ten to fifteen minutes. The filling material 
may consist of from 7-9 per cent, of sal soda solution, 
36** -37" B. warm or just enough to close up the soap and 
make it rise high in the center of a screw crutcher and 
make it cling close to a warm trowel. Other fillers such 
as outlined below are added at this point. 

52 



CLASSIFICATION OF SOAPS 

An addition of from 2-3 per cent, of a special mineral oil 
for this purpose will impart a finish to the soap and 3-5 
per cent, starch added prevents the soap from cracking in 
the frames. Other filling material as silicate of soda, borax, 
talc or silex are used. After the filling material has been 
thoroughly crutched through the soap it is framed, and, 
after being several days in the frame to solidify and cool 
the soap is ready for slabbing, pressing and wrapping. 

In order to more definitely illustrate the composition of 
the mixture of fats and oils entering into the formation of 
a laundry soap a typical formula may be given for such 
a soap containing 40 per cent, rosin added to the amount 
of fats used: 

lbs. 

Grease 7,000 

Tallow 4,000 

Corn Oil 7,000 

Cottonseed Oil 3,000 

Rosin 8,400 

The following have been found to be satisfactory filling 
materials and are calculated upon the basis of a 1,400-pound 
frame of soap. 

I. lbs. 

Sodium Silicate, 38^-40° B 100 

Mineral Oil 25 

Sal Soda Solution, 36° B 80 

Borax 1 

11. 

Sal Soda Solution, 36° B 80 

Mineral Oil 25 

Sodium Silicate 60 

53 



r 



SOAP-MAKING MANUAL 

III. 

Soda Ash 10 

Sal Soda 55 

Sodium Silicate 115 

Mineral Oil 40 

Brine (Saturated Solution) 10 

IV. 

Sodium Silicate 100 

Silex or Talc 200 

Soda Ash 50 

V. 

Sal Soda Solution, 36° B 90 

Sodium Silicate 50-60 

Mineral Oil 25 

Borax Solution, 25° B. (hot) 15 

CHIP SOAP. 

Chip soap is used extensively in laundries but is also 
used largely in other branches. It may be made either 
as a settled soap or by the cold made process. 

To make a full boiled settled chip soap, proceed as 
directed under settled laundry soap. The kettle is stocked 
with light grease or a mixture of grease with corn oil or 
other cheap oils. For this kind of soap the rosin is elim- 
inated. 

Chip soap may be filled as well as laundry soap. This 

is done in the crutcher and the following adulterations are 

suitable. ,. 

lbs. 

Settled Soap 700 

Soda Ash 35 

Sodium Silicate 215 

or 

Settled Soap 700 

54 



^ 



CLASSIFICATION OF SOAPS 

Silicate of Soda 560 

Soda Ash 18 

Carbonate of Potash, 26° B 50 

The cheapest method of drying is by running this soap 

through a drying machine and this is the procedure usually 

carried out for making dried chip soap. 

COLD MADE CHIP SOAPS. 

To make chip soaps by the cold process a sweet tallow of 
low percentage of free fatty acid should be employed. The 
tallow is heated to 120" to 135" F. and the lye run in 
slowly at first and then the silicate of soda is added. The 
mass is then mixed until a finger drawn through the 
soap leaves a slight impression, then dropped into frames 
or barrels. Soaps containing a small percentage of fat 
should be well covered in the frame for twenty-four hours 
to retain their heat and insure proper saponification. The 
following formulae are suitable: 

I. lbs. 

Tallow 1,200 

Soda Lye, 25" B 850 

Sodium Silicate 750 

n. 

Tallow 475 

Ceylon Cocoanut Oil 100 

Soda Lye, 37" B 325 

Potash Lye, 37" B 56 

IIL 

Tallow 500 

Soda Lye, 37y2" B 297 

Sodium Silicate 416 

Potash Lye, 37y2" B 37j4 

55 



r 



SOAP-MAKING MANUAL 

IV. 

Tallow 450 ^ 

Soda Lye, 37^* B 255 * 

Sodium Silicate 450 a 

Potash Lye, 37y2* B 50 i 



V. 

Tallow 450 

Soda Lye, 35** B 470 

Sodium Silicate 650 






"J 






VI. 

Tallow 420 

Sodium Silicate 600 

Soda Lye, 37^° B 270 ^ 

■«•♦( 

UNFILLED CHIP SOAP. ix 

A very good grade of chip soap is made by employing i*^ 
no filling material whatsoever, but unfortunately the price i*^i 
of this soap has been cut to such an extent that these can ^^^^i 
not compete with a filled chip. A number of the best soaps * ! 
of this kind are made from a settled soap using a light ^« 
grease with corn oil. A soap of this nature is made as "^P 
follows. '^i 

lbs. 5or? 

Settled Soap 800 |io ij 

Sal Soda Solution, 36''-37** B 252 iecn 

Soda Ash 182 

If this soap is run into frames it may be stripped and 
chipped in two days. 



In 



SOAP POWDERS. 



pulv 

5tVC 

Soap powders have become so great a convenience ciall 
as a general cleansing agent that to eliminate them tiiei 
from the household necessities would mean much un- i^ 

56 



^ 



Lt 



CLASSIFICATION OF SOAPS 

"X\e.oessary energy and work to the great number of 
consumers of this product. They may be manufactured so 

■2 V\eaply and still be efficient, that their use has almost 

become universal for cleansing and scouring purposes. 

^ T*lie uses to which soap and scouring powders are adapted 

are too well known to enter into a description of their 

employment. Since they offer a greater profit to the man- 

^ uf acturer than ordinary household soap, masy brands are 

j^ extensively advertised. 

S Numerous combinations for soap powders might be cited 

and it is a simple matter to vary the ingredients as to 

fat content and manufacture a powder of this sort as low 

_ & as a cent a pound. Many substances are incorporated with 

...^ soap, such as salt, soda ash, tripoli, crushed volcanic de- 

^ posits, ground feldspar, infusorial earth of various kinds, 

silex, etc. In addition to these various fillers, compounds 

with true cleansing and bleaching properties, in addition to 

j^)jtm^ soap, are added, such as the salts of ammonium (sal am- 

rijijttlyiii'^ moniac, carbonate of ammonia), sodium perborate and 

r\^[W ii^Q peroxides of various metals. The public, however, 

■^'^^^ have been accustomed to receive a large package of 

ijDsiii?*'^ soap or scouring powder for a small amount of money 

.jiitfiR^''^ and it is a difficult matter for the manufacturer to add 

more expensive substances of this nature to his product, 

^ to increase its efficiency, without raising the price or 

^ decreasing the size of the package. 

S In manufacturing soap powders, the dried soap chips 

..^ might be mixed with the filler and alkali and then 

ujtiifH pulverized. This method is not extensively employed 

nevertheless. The process which is the most economical 

is one whereby the ingredients are mixed in a spe- 

^ J. cially adapted mixer for heavy material until dry and 

Ai^^x^ then run directly to the crusher and pulverizer, after 

'■■rj.* which it is automatically packed, sealed and boxed 



. J 



SOAP-MAKING MANUAL 

Another method of procedure is to run out the mix- 
ture from the crutcher to the frames, which are stripped 
before the soap cools, and is cut up at once, for if it 
hardens it could not be cut with wires. It is better, how- 
ever, to run the mixture into sheets upon a specially con- < 
structed floor and break up the mass when cool. } 

Formulae for soap powders which have been found 
to be suitable for running dry in the mixer follow: 

I 

Soda ash, 58 per cent 42 lbs. 

Silica 220 " 

Settled soap (usually cottonseed). 25 " 
Salt 10 " 

II 

Soap (settled cottonseed) 40 lbs. 

Soda ash, 58 per cent 60 " 

III 

Settled soap 100 lbs. 

Soda ash, 58 per cent 400 " 

Fillers in varying proportions may replace the soda 
ash in the above formulae. It is of course understood 
that the soap has been previously made and run as 
molten soap into the crutcher. 

The following soap powders will not dry up in the 
crutcher upon running, but are of the class which may 
be framed or run on the floor to solidify: 

I 

Soap 850 lbs. 

Filler 400 " 

Sal soda solution, 20 degs. B 170 " 

58 






CLASSIFICATION OF SOAPS 

II 

Soap 650 lbs. 

Filler 550 

Sal soda solution, 20 degs. B 340 

III 

Soap 80 lbs. 

Filler 550 " 

Sal soda solution 170 " 

IV 

Soap (settled tallow) 800 lbs. 

Filler 400 " 

Sal soda solution 170 " 

Water 100 " 

V 

First saponify 100 parts house grease and 100 parts 
ordinary grease and make a run soap. Then use in 
crutcher either: 

Soap '. . . 400 lbs. 

Filler 575 " 

Hot water 60 " 

or 

Soap 200 lbs. 

Hot water 200 " 

Filler 625 " 

It would be a simple matter to write numerous addi- 
tional formulae, but the above are typical. The manu- 
facturer must judge for himself just what filling 
material to use. The filler indicated in the above 
formulae is therefore left open. A few formulae for 
more expensive powders than those given recently ap- 
peared among others in the "Seifensieder Zeitung"*; 

♦Scifensieder Ztg.. 40. 47. 1266 (1913). 

59 



SOAP-MAKING MANUAL 

I 

Powdered soap 90 lbs. 

Sodium perborate 10 " 

The perborate should be added when the powder is 
perfectly dry or it loses its bleaching: properties. 

II 
Soap powder, 20 per cent. fat. 

Cocoanut oil fatty acids 25 lbs. 

Olein 25 " 

Bone fat 70 " 

Soda lye, 30 degs. B 90 " 

Water 150 " 

Ammonium carbonate 125 " 

HI 
Soap powder, 10 per cent. fat. 

Cocoanut oil fatty acids 20 lbs. 

Olein 10 " 

Bone fat 20 " 

Soda lye. 30 degs. B 30 " 

Water 175 " 

Ammonium carbonate 175 " 

LIGHT OR FLUFFY POWDERS. 

Light or fluffy powders containing 35-45% moisture can 
be made in two ways. The first method requiring a min- 
imum equipment is to mix the powder and sal soda in a 
mixer, allow it to stand in frames for a week to crystallize 
or spread it on the floor for a few hours to dry and then 
grinding it. 

The continuous method finishes the powder in a few min- 
utes and with a minimum amount of labor. By this 
process the various ingredients, soap, soda ash splution, etc., 
are measured, run by gravity into the mixer, mixed and the 
molten mass run over the crystalHzer or chilling rolls thru 

60 



CLASSIFICATION OF SOAPS 

which either cold water or brine is pumped. From the roll 
the powder is scraped off clean ab y knife, passes to a 
screen which sends the tailings to a grinder, falls into a 
storage bin from whence it is weighed and packed by an 
automatic weighing machine into cartons made up in most 
cases by another machine. Due to the large percentage of 
moisture contained in these soap powders the carton is 
generally wrapped in wax paper to aid in the prevention of 
the escape of moisture. 

Scouring Powders. 
Scouring powders are very similar to soap powders and 
differ only in the filler used. We have already considered 
these fillers under scouring soap, from which they do not 
differ materially. They are usually insoluble in water to 
aid in scouring. The mixer used for substances of this 
kind in incorporating the soap and alkali must be of 
strong construction. 

SCOURING SOAP. 

Scouring soaps resemble soap powders very closely 
in their composition, in that they are a combination of 
soap and filling material. Since more lather is required 
from a scouring soap than in soap powders, a cocoa- 
nut oil soap is generally used. The usual filling ma- 
terial used is silex. The greatest difficulty in the manu- 
facture of scouring soap is the cracking of the finished 
cake. This is usually due to the incorporation of too 
great an amount of filler, or too high a percentage of 
moisture. 

In manufacturing these soaps the cocoanut oil is 
saponified in the crutcher with 38 degs. B. lye, or 
previously saponified as a run soap, as already de- 
scribed under "Marine Soaps." To twenty-five parts 
of soap are added a percentage of 38 degs. B. sal soda 

61 



SOAP-MAKING MANUAL 

or soda ash solution, together with a small quantity of 
salt brine. To this mixture in the crutcher seventy-five 
parts of silex are then added, and a sufficient amount of 
hot water to make the mass flow readily. Care must 
be exercised to not add too great a quantity of water 
or the mass will crack when it cools. The mass is 
then framed and cut before it sets, or poured into 
molds and allowed to set. While silex is the most 
extensively used filler for scouring soaps, it is feasible 
to incorporate other substances of like character, al- 
though it is to be remembered that the consumer is accus- 
tomed to a white cake, such as silex produces. Any 
other material used to replace silex should also be as 
fine as this product. 

FLOATING SOAP. 

Floating soap occupies a position midway between laun- 
dry and toilet soap. Since it is not highly perfumed and 
a large piece of soap may be purchased for small cost, as 
is the case with laundry soap, it is readily adaptable to 
general household use. Floating soap differs from ordinary 
soap in having air crutched into it which causes the soap 
to float in water. This is often advantageous, especially 
as a bath soap, and undoubtedly the largest selling brand 
of soap on the American market today is a floating soap. 

In the manufacture of floating soap a high proportion of 
cocoanut oil is necessary. A most suitable composition is 
one part cocoanut oil to one part of tallow. This is an 
expensive stock for the highest grade of soap and is VFSually 
cheapened by the use of cottonseed or various other liquid 
oils. Thus it is possible to obtain a floating soap from a 
kettle stocked with 30 per cent, cocoanut oil, 15 per cent, 
cottonseed oil and 55 per cent, tallow. With this quality 
of soap, however, there is a possibility of sweating and 

62 



CLASSIFICATION OF SOAPS 

rancidity, and of the soap being too soft and being poor 
in color. 

The process of manufacture is to boil the soap in an or- 
dinary soap kettle, after which air is worked into the hot 
soap by a specially constructed crutcher, after which the 
soap is framed, slabbed, cut into cakes and pressed. 

Concerning the boiling of the soap, the saponification 
must be carefully carried out, as the- high proportion of 
cocoanut oil may cause a violent reaction in the kettle caus- 
ing it to boil over. 

The method of procedure is the same as for a settled 
soap up to the finishing. When the mass is finally settled 
after the finish, the soap should be more on the '*open" side, 
and the object should be to get as long a piece of goods 
as possible. 

Due to its high melting point, a much harder crust 
forms on the surface of a floating soap and in a greater 
proportion than on a settled soap during the settling. In a 
large kettle, in fact, it has been found impossible to break 
through this crust by the ordinary procedure to admit the 
skimmer pipe. Much of the success of the subsequent opera- 
tions depends upon the completeness of the settling, and in 
order to overcome the difficulties occasioned by the forma- 
tion of the crust everything possible should be done in the 
way of covering the kettle completely to enable this period 
of settling to continue as long as possible. 

When the soap is finished it is run into a specially con- 
structed U-shape crutcher, a Strunz crutcher is best adapt- 
ed to this purpose, although a rapidly revolving upright 
screw crutcher has been found to give satisfaction upon a 
smaller scale, and a sufficient quantity of air beaten into 
the soap to make it light enough to float. Care must be 
taken not to run the crutcher too rapidly or the soap will 
be entirely too fpbby. During this operation the mass of 

63 



SOAP-MAKING MANUAL 

soap increases in bulk, and after it has been established 
how much air must be put into the soap to satisfy the re- 
quirements, this increase in bulk is a criterion to estimate 
when this process is completed. 

It is of course understood that the longer the crutching 
continues the greater quantity of air is incorporated and the 
increase of volume must be established for a particular 
composition by sampling, cooling the sample rapidly and 
seeing if it floats in water. If the beating is continued too 
long an interval of time, the finished soap is too spongy 
and useless. 

The temperature of the mass during crutching is most 
important. This must never exceed 158 degrees F. At 
159 degrees F. the operation is not very successful, yet 
the thermometer may indicate 140 degrees F. without inter- 
fering with this operation. If, however, the temperature 
drops too low, trouble is liable to be met with, by the soap 
solidifying too quickly in the frames. 

When the crutching is completed, the soap is allowed 
to drop into frames through the valve at the bottom of the 
cnitcher and rapidly crutched by the hand in the frames 
to prevent large air spaces and then allowed to cool. It 
is an improvement to jolt the frames as they are drawn 
away as this tends to make the larger air bubbles float to 
the surface and thus reduce the quantity of waste. When 
the soap has cooled, the frame is stripped and the soap 
slabbed as usual. At this point a layer of considerable 
depth of spongy soap will be found to have formed. This 
of course must be cut away and returned to the kettle. 
The last few slabs are also often rejected, inasmuch as 
the weight of the soap above them has forced out so much \ 

of the air that the soap no longer floats. As a fair average 
it may be estimated that not more than 50 to 60 per cent, 
of the soap in the kettle will come out as finished cakes^ 

64 i 



CLASSIFICATION OF SOAPS 

the remaining 40 to 50 per cent, being constituted by the 
heavy crust in the kettle, the spongy tops, the botton slabs 
and scrapings. This soap is of course reboiled and con- 
sequently not lost, but the actual cakes obtained are pro- 
duced at a cost of practically double labor. 

It is advisable to add a small quantity of soap blue color 
to the mass while crutching to neutralize the yellowish 
tint a floating soap is liable to have. 

Some manufacturers add a percentage of carbonate of 
soda, about 3 per cent., to prevent the soap from shrinking. 
Floating soap may also be loaded with sodium silicate to 
the extent of about 5 per cent. 

TOILET SOAP. 

It is not a simple matter to differentiate between toilet 
soaps and various other soaps, because numerous soaps are 
adaptable to toilet purposes. While some soaps of this 
variety are manufactured by the cold made or semi-boiled 
process, and not milled, the consumer has become accus- 
tomed to a milled soap for general toilet use. 

The toilet base most extensively employed is a tallow 
and cocoanut base made as a full boiled settled soap. The 
manufacture of this base has already been outlined and 
really needs no further comment except that it is to be 
remembered that a suitable toilet soap should contain no 
great excess of free alkali which is injurious to the skin. 
Cochin cocoanut oil is preferable to the Ceylon cocoanut 
oil or palm kernel oil, to use in conjunction with the tal- 
low, which should be a goocf grade and color if a white 
piece of goods is desired. The percentage of cocoanut oil 
may be anywhere from 10 to 25 per cent., depending upon 
the kind of lather required, it being remembered that co- 
coanut oil increases the lathering power of the soap. 

In addition to a tallow base, numerous other oils are 

65 



SOAP-MAKING MANUAL 

used in the manufacture of toilet soaps, especially palm 
oil, palm kernel oil, olive oil and olive oil foots, and to a 
much less extent arachis or peanut oil, sesame oil and 
poppy seed oil, oils of the class of cottonseed, corn and 
soya bean oils are not adapted to manufacturing a milled 
soap, as they form yellow spots in a finished cake of soap 
which has been kept a short time. 

Palm oil, especially the Lagos oil, is much used in mak- 
ing a palm base. As has already been stated, the oil is 
bleached before saponification. A palm base has a yel- 
lowish color, a sweetish odor, and a small quantity added 
to a tallow base naturally aids the perfume. It is especially 
good' for a violet soap. The peculiarity of a palm oil base 
is that this oil makes a short soap. By the addition of 
some tallow or twenty to twenty-five per cent, of cocoanut 
oil, or both, this objection is overcome. It is a good plan 
in using a straight palm base to add a proportion of yellow 
color to hold the yellowish tint of this soap, as a soap made 
from this oil continues bleaching upon exposure to air and 
light. 

Olive oil and olive oil foots are used most extensively 
in the manufacture of castile soaps. The peculiarity of an 
olive oil soap is that it makes a very slimy lather, and like 
palm oil gives the soap a characteristic odor. An olive 
oil soap is usually considered to be a very neutral soap 
and may readily be superfatted. Much olive oil soap is 
used in bars or slabs as an unmilled soap and it is often 
made by the cold process. Peanut oil or sesame and poppy 
seed oil often replaces olive oil, as they form a similar 
soap to olive oil. 

In the manufacture of a toilet soap it is hardly practical 
to lay down a definite plan for the various bases to be 
made. From the combination of tallow, palm oil, cocoanut 
oil, palm kernel oil, olive oil and olive oil foots, a great 

66 



CLASSIFICATION OF SOAPS 

many bases of different proportions might be given. The 
simplest method is to make a tallow base, a palm base and 
an olive oil base. Then from these it is an easy matter 
to weigh out any proportion of these soap bases and ob- 
tain the proper mixture in the mill. If, however, as is 
often the case, a large quantity of soap base of certain pro- 
portions of these, four or even more of these fats and oils 
is required, it is not only more economical to stock the 
kettle with the correct proportion of these oils, but a more 
thorough mixture is thus obtained *>y saponifying these in 
the kettle. In view of the fact that it is really a question 
for the manufacturer to decide for himself what combina- 
tion of oils he desires for a particular soap we will simply 
outline a few typical toilet soap bases in their simplest 
combination. It is understood that these soaps are suitable 
for milled soaps and are to be made as fully boiled settled 
soaps. Palm kernel oil may be substituted for cocoanut 
oil in all cases. 

TALLOW BASE. 

Tallow 75-90 parts 

Cocoanut oil 25-10 parts 

PALM BASE. 

Bleached Lagos palm oil 75-80 parts 

Cocoanut oil 25-20 parts 

or 

Tallow 30 parts 

Palm oil 60 parts 

Cocoanut oil 10 parts 

OLIVE OIL BASE (WHITe). 

Olive oil 75-^ parts 

Cocoanut oil 25-10 parts 

or 

67 



SOAP-MAKING MANUAL 

Olive oil 40 parts 

Tallow 40 parts 

Cocoanut 20 parts 

Where a green olive oil base is desired, olive oil foots 
are substituted for the olive oil. Peanut oil may replace 
the olive oil or part of it, the same being true of sesame 
oil and poppy seed oil. 

PALM AND OLIVE BASE. 

Palm oil 50 parts 

Olive oil 30 parts 

Cocoanut oil 20 parts 

or 

Palm oil 20 parts 

Olive oil 10 parts 

Tallow 50 parts 

Cocoanut oil 20 parts 

CHEAPER TOILET SOAPS. 

It is often necessary to manufacture a cheaper grade of 
soap for toilet purposes to meet the demand of a certain 
class of trade as well as for export. To accomplish this 
it is of course necessary to produce a very inferior product 
and run down the percentage of fatty acids contained in 
the soaps by the addition of fillers or to use cheaper oils in 
manufacturing. The most simple method of filling a soap 
is to load it at the mill with some substance much less ex- 
pensive than the soap itself. Many of the cheaper toilet 
soaps, however, are not milled and it is, therefore, neces- 
sary to follow out some other procedure. 

Milled soaps, as has just been stated, are loaded at the 
mill. The consumers of cheaper toilet soaps in this 
country are accustomed to a milled soap and this grade 
of soap for home consumption is very often filled with 

68 



CLASSIFICATION OF SOAPS 

numerous substances, but most generally by adding starch 
and talc. The addition of such materials of course later 
exhibit themselves by imparting to the cake of soap a 
dead appearance. Talc is more readily detected in the 
soap than starch by washing with it, as talc is insoluble and 
imparts a roughness to the soap, like sand or pumice, as 
the soap wears down. It may readily be added to 20 per 
cent, by weight. Starch is to be preferred to talc, in load- 
ing a soap, as it is not so readily noticeable in washing. It 
leaves the cake itself absolutely smooth although the lather 
formed is more shiny. This substance may be employed to 
as high a percentage as one-third the weight of the soap. 
It is, of course, possible to cheapen the best soap base by 
this method and the price may be further lowered by using 
the less expensive oils and fats to make the soap base. 

RUN AND GLUEP UP SOAPS. 

A very cheap grade of soap may be made by making a 
run soap and adding the filler e. g. sodium silicate in the 
kettle during saponification. The percentage of fatty acids 
may be brought down to 10 per cent., although of course 
a soap of this type shrinks a whole lot upon exposure. 

In making a ''glued up'' soap the procedure is the same 
for making the soap itself as with a settled soap, except 
that the soap is finished "curd" and later filled in the 
crutcher. The percentage of fatty acids in a soap of this 
type is seldom below 50 per cent. 

The method of "gluing up" a soap is best illustrated by a 
typical soap of this character in which the kettle is charged 
with the following stock. 

Bleached palm oil 5 parts 

Distilled grease 2 " 

Cotton oil foots stock, 63% fatty acid. 1 " 
^ Rosin 4 " 

69 



SOAP-MAKING MANUAL 

The palm oil is first run into the kettle, saponified and 
washed to extract any glycerine, then the rest of the fats 
and finally the rosin. The soap is then finished and settled 
as with a boiled settled soap. To assure success it is 
absolutely necessary that the soap settle as long a period 
as possible, or until the temperature is about 150 degs. F. 
The ideal temperature for carrying out the "gluing up" 
process is 140 degs. R, as at a lower temperature than 
this the soap is liable to cool too quickly and not be 
thoroughly glued up. A higher temperature than 150 degs. 
F. causes delay in that the soap does not properly take the 
filler at a higher temperature and the soap must be kept in 
the crutcher until the temperature drops to the right point. 

The soap is run into the crutcher and the percentage of 
fatty acids run down to 50-55 per cent, with one of the 
following mixtures : 

Sodium silicate, S9j4° B 1 part 

Potassium carbonate, 51® B 1 " 

or 

Sodium silicate, 59H** B 1 part 

Potassium carbonate, 51** B 1 " 

Sodium sulfate, 28** B 1 " 

From 230 to 300 pounds of either of these mixtures arc 
required for a crutcher holding 2,600 pounds of soap. 

The crutching is continued until the mass is well "spiked," 
that is to say, a freshly broken surface of the soap, as 
the crutcher blade is jerked away, stands up like shattered 
sheets in triangular form (A A A), which retain their 
shape perfectly. When this condition is realized the soap 
is run into frames which are carefully crutched by hand 
to remove any air spaces. The surface of the soap is then 
smoothed down and heaped up in the center. After stand- 
ing a day to contract, the surface is again leveled and a 

70 ^__ 



CLASSIFICATION OF SOAPS 

snugly-fitting board placed on the top of the soap upon 
which a weight is placed or upon which the workman 
treads and stamps until the surface is flat, thus assuring 
the further removal of air spaces. The soap remains in 
the frame from six to eight days and is then slabbed, 
barred and pressed by the usual method employed for 
soaps thus handled without milling. 

In a soap of this nature no hard and fast rule can be 
laid down as to the quantity of solution to be used for 
"gluing up" or the strength of the solution. In a soap of 
the type described the most satisfactory appearing cake 
will be obtained from a soap containing 58 per cent, fatty 
acids. That is to say, about 8 per cent, to 10 per cent, filling 
solution is added per hundred pounds of soap. The filling 
solutions given are very satisfactory. Carbonate of soda 
should be avoided in connection with sodium silicate as the 
property of efflorescing on the surface of the finished cake 
after a short time will prove detrimental. To assure suc- 
cessful gluing up it is advisable to experiment upon a 
\ small scale to determine the exact extent to which the 
j filling solution should be diluted. Various proportions of 
water are added to a certain quantity of the filled soap. 
i After the soap has been filled in a small receptacle a 
I sample is taken and rubbed between the fingers. If the 
freshly exposed surface is smooth and glossy, the filling 
solution is weak enough, if rough it is too strong. It is 
of course understood that the temperature must be correct, 
140 degs. to 150 degs. R, or the soap will be rough. By this 
means the operator can readily judge the correct strength 
of his filling solution. When properly carried out a per- 
fectly satisfactory soap is obtained. 

CURD SOAP. 

The object of a soap which is finished "curd" or grained, 
is to obtain a harder piece of goods from low titer fat or 

71 



SOAP-MAKING MANUAL 

Id increase the percentage of fatty acids in the finished 
soap. This is still another method of producing a cheap 
grade of soap as by its adoption the cheaper oils and fats 
may be used to obtain a firm piece of soap. 

A typical charge for curd soap is: 

Red oil 63 parts 

Tallow 10 " 

Rosin 27 " 

Cotton seed foots may be employed in place of red oil 
and a tallow of too high titer is not suitable for this kind 
of soap. 

The red oil and tallow are first saponified with 15 degs. 
B. lye, boiler pressure 80-90 pounds, 18 degs. B. lye for 
lower steam pressure, and two washings given to extract 
the glycerine. The rosin is added at the strengthening 
change and at the finish the soap is "pitched," that is to 
say, the soap is settled over night only. The next day the 
lyes are drawn off and a portion of the nigre pumped to 
another kettle which prevents later streaking of the soap. 
The soap is then boiled with 18 degs. B. lye as with 
another strengthening change under closed steam. Salt 
brine or "pickle," 15 degs. B. is then added and the mass 
boiled with closed steam until the brine reaches a density 
of 18 degs. B. and the kettle pumped the next day. A 
soap of this type requires either hand or power crutching 
to assure homogeneity and prevention of streaks. To ob- 
viate any air spaces it is advisable to place over the top 
of the frame a tightly-fitted board which is heavily 
weighted down. This soap is also pressed without any 
milling. 

COLD MADE TOILET SOAPS. 

Comparatively little toilet soap is made by the cold or 
•cmi-boiled processes. While thest are the simplest 

72 



CLASSIFICATION OF SOAPS 

methods of manufacturing soaps the drawbacks of using 
them are numerous and only in a few cases are they very 
e^ftensively employed. To make a toilet soap by the cold 
process a combination of good grade tallow and cocoanut 
oil is required. It requires 50 per cent, by weight of 36 
degs. B. lye to saponify a given weight of tallow and 50 
per cent, of 38 degs. B. lye for cocoanut oil. The lyes 
are used full strength or may be reduced slightly with 
water and the method of procedure is the same as already 
given in the general directions for cold made soaps. 

Cold made soaps are readily filled with sodium silicate 
which is added at the same time the stock is put into the 
crutcher. In adding the silicate it is necessary to add 
additional lye to that required for saponifying the fats, 
about 20 per cent, of 36 degs. B. lye is the proper amount. 
There is of course a certain amount of shrinking due to 
the addition of this filler and the finished cake is exceed- 
ingly hard, yet the author has seen a good looking cake of 
cheap soap made from as high a proportion as 420 parts 
of tallow to 600 parts of silicate. 

Cold made soaps are usually pressed without milling, 
although it is readily feasible to mill a cold made soap 
provided it is not a filled soap such as has just been 
described. 

PERFUMING AND COLORING TOILET SOAPS. 

Equally important as the soap itself or even to a greater 
extent is the perfume of a toilet soap. A prominent manu- 
facturer recently made the statement, which is often the 
truth, that it makes no difference to the public what kind 
of soap you give them, as long as you put plenty of odor 
into it The perfuming of soaps is an art in itself and a 
subject to be treated by one versed in this particular 
branch. We can only take into account the importance of 

73 



SOAP-MAKING MANUAL 

the perfume as related to toilet soap not only, but the ne- 
cessity of adding a certain proportion of the cheaper 
products of odoriferous nature to laundry soap to cover 
and disguise the odor of even this type of soap. 

The price of a cake of toilet soap to a great extent de- 
pends upon the perfume, and the manufacturer should aim 
to give the best possible perfume for a certain price. He 
should not allow his personal likes or dislikes to enter into 
the judgment of whether an odor is good or not, but sub- 
mit it to a number of persons to obtain the concensus of 
opinion. In giving or selling a piece of soap to the con- 
sumer, it is second nature for him to smell it, and in the 
great majority of cases his opinion is formed not from any 
quality the soap itself may have during use, but from the 
odor. This only emphasizes the fact that the perfume 
must be pleasing, not to one person, but to the majority, 
and many brands owe their popularity to nothing more 
than the enticing perfume. 

Perfuming of soap is closely allied to the soap making 
industry, but as stated a branch in itself. It is, therefore, 
not our purpose to give numerous formulae of how to 
perfume a soap, but rather to advise to go for information 
to some one who thoroughly understands the character- 
istics of the numerous essential oils and synthetics and give 
positive information for the particular odor desired. Un- 
der no circumstances is it advisable to purchase a perfume 
already compounded, but since all perfumes are a blend of 
several or many essential oils and synthetics, it is a more 
positive assurance of obtaining what is desired, by pur- 
chasing the straight oils and blending or mixing them as 
one desires. 

The perfume is added to a milled soap just before the 
milling process in the proper proportion per hundred 
pounds of soap. In cold made or unmilled soaps it is 

74 



CLASSIFICATION OF SOAPS 

* 

added in the crutcher while the soap is still hot. By this 

method, of course, a proportion of the perfume is lost due 

to its being more or less volatile. 

COLORING SOAP. 

While much toilet soap is white or natural in color, 
many soaps are also artificially colored. The soap colors 
used for this purpose are mostly aniline dyestuffs. The 
price of these dyestuffs is no criterion as to their quality, 
as the price is usually regulated by the addition of some 
inert, water soluble substance like common salt or sugar. 

The main properties that a dyestuff suitable for produc- 
ing a colored soap should have are fastness to light and 
to alkali. They should further be of such a type that the 
color does not come *off and stain a wash cloth or the 
hands when the soap is used and should be soluble in 
water. Under no circumstances is it advisable to add 
these in such a quantity that the lather produced in the 
soap is colored. It is customary to first dissolve the 
dye in hot w^ater as a standardized solution. This can 
then be measured out in a graduate and added to the soap 
the same time as the perfume is put in. About one part 
of color to fifty parts of water is the propor proportion 
to obtain a perfect solution, though this is by no means 
fixed. In making up a solution thus it is an improvement 
to add to the same about one-half of one per cent, of an 
alkali either as the hydroxide or carbonate. Then, if there 
is any possibility of change of color due to alkalinity of 
the soap, it will exhibit itself before the color is added. 

A particularly difficult shade to obtain is a purple, as 
there is up to the present time no purplish aniline color 
known which is fast to light. Very good results in soap 
may be obtained by mixing a fast blue, as ultramarine or 
cobalt blue, with a red as rhodamine or eosine. 

75 



r 



SOAP-MAKING MANUAL ^ 

Inasmuch as the colors for soap have been carefully 
tested by most of the dyestuff manufacturers, and their 
information, usually reliable, is open to any one desiring 
to know about a color for soap, it is better to depend upon 
their experience with colors after having satisfied one's 
self that a color is what it is represented for a particular 
shade, than to experiment with the numerous colors one's 
self. 

MEDICINAL SOAPS. 

Soap is often used for the conveyance of various 
medicants, antiseptics or other material presumably 
beneficial for treatment of skin diseases. While soap 
is an ideal medium for the carrying of such materials, 
it is an unfortunate condition that when incorporated 
with the soap, all but a very few of the numerous sub- 
stances thus employed lose their medicinal properties 
and effectiveness for curing skin disorders, as well as 
any antiseptic value the substance may have. Soap 
is of such a nature chemically that many of the sub- 
stances used for skin troubles are either entirely de- 
composed or altered to such an extent so as to impair 
their therapeutic value. Thus many of the claims made 
for various medicated soaps fall flat, and really have 
no more antiseptic or therapeutic merit than ordinary 
soap which in itself has certain germicidal and cleaning 
value. 

In medicating a soap the material used for this pur- 
pose is usually added at the mill. A tallow and cocoanut 
oil base is best adapted for a soap of this type. The 
public have been educated more or less to the use of 
colored soap to accentuate its medicinal value, and green 
is undoubtedly the most popular shade. This inference, 
however, is by no means true for all soaps of this 

76 



1 



CLASSIFICATION OF SOAPS 

character. Possibly the best method of arranging these 
soaps is briefly to outline some medicinal soaps. 

SULPHUR SOAPS. 

The best known sulphur soaps contain anywhere from 
one to 20 per cent, of flowers of sulphur. Other soaps 
contain either organic or inorganic sulphur compounds. 

TAR SOAP. 

The tar used in the manufacturing of tar soap is ob- 
tained by the destructive distillation of wood, the pine 
tar being the most extensively employed. While the 
different wood tars contain numerous aromatic com- 
pounds, such as phenols, phenyl oxides, terpenes and 
organic acids, these are present in such a slight pro- 
portion so as to render their effectiveness practically 
useless. It has, therefore, been tried to use these 
various compounds contained in the tar themselves to 
make tar soap really effective, yet tar is so cheap a 
substance that it is usually the substance used for 
medicating a tar soap. About 10 per cent, of tar is 
usually added to the soap with 2 ounces of lamp black 
per hundred pounds of soap. 

SOAPS CONTAINING PHENOLS. 

Phenol (Carbolic Acid) is most extensively used in 
soaps of this kind, which are called carbolic soaps. 
Carbolic soaps are generally colored green and contain 
from 1 to 5 per cent, phenol crystals. 

The cresols are also extensively used for making 
soaps named carbolic. These substances impart more 
odor to the soap and really have more disinfecting 
powers than phenol when incorporated with soap. 

Other soaps, containing the phenol group, which are 
well known are resorcinol soap, salol soap, thymol soap, 



/ 



SOAP-MAKING MANUAL 

naphthol soap, etc. From one to five per cent of the 
compound after which the soap is named is usually 
incorporated with the soap. 

PEROXIDE SOAP. 

Hydrogen peroxide in itself is an excellent disin- 
fectant. It loses all its medicinal value, however, when 
added to the soap. To overcoipe this objection various 
metallic peroxides are added to the soap, as sodium 
peroxide, zinc peroxide and barium peroxide. These 
generate hydrogen peroxide by the addition of water. 
Sodium perborate is also used in peroxide soaps, as this 
substance is decomposed by water into hydrogen per- 
oxide and sodium metaborate. 

MERCURY SOAPS. 

Mercuric chloride (corrosive sublimate) is most ex- 
tensively used for the production of mercury soaps. 
Because of its extremely poisonous properties care 
should be taken in using it. Since it really eventually 
loses any antiseptic value in the soap through forming 
an insoluble mercury soap it might better be omitted 
entirely. 

LESS IMPORTANT MEDICINAL SOAPS. 

While the above mentioned soaps are probably the 
best known medicated soaps, there are numerous other 
soaps which may be classed under these kinds of soaps. 
Thus we have cold cream soap, which can be made by 
adding Russian Mineral Oil, 1 to 5 per cent., to the 
soap; witch hazel soap, made by the addition of extract 
of witch hazel ; iodine soap, made by adding iodine or 
iodoform; formaldehyde soap, made by adding for- 
maldehyde; tannin soaps, made by adding tannin. In 
fact, there have been incorporated in soap so great a 

78 



CLASSIFICATION OF SOAPS 

number of substances that the list might be greatly 
enlarged. 

Medicated soaps are not only used in solid form, but 
in powder, paste and liquid soap as well. The only 
difference in a soap like those just referred to is that 
the medicant is incorporated with these forms of soaps 
as convenience directs. 

CASTILE SOAP. 

A pure castile soap should be made from olive oil. 
This, however, is not always the case, as a number of 
oils as well as tallow are used to adulterate this oil to 
cheapen it, and there are even some soaps called castile 
which contain no olive oil at all. Most of the pure 
castile soap used in this country is imported, as it is a 
difficult matter for the American manufacturer to com- 
pete with the pure imported castile soap, since both 
labor and oil itself are so much cheaper in the vicinities 
of Europe where this oil ^s produced, that this advantage 
is more than compensated by the carrying and custom 
charges by importing the castile soap. 

Castile soap may be made either by the full boiled or 
cold process. There are numerous grades of olive oil, 
and those used for soap making are denatured to lower 
the duty charges. Olive oil makes a hard white soap, 
usually sold in bars, and olive oil foots a green soap, 
due to the coloring matter contained in this oil. 

To make a boiled castile soap, a composition of 10 
per cent. Cochin cocoanut oil and 90 per cent, olive oil 
may be used. To cheapen this, peanut oil (Arachis oil) 
may entirely replace the olive oil, or about 20 per cent, 
of corn or soya bean oil may be added. The oils are 
saponified as usual in making a settled soap and to 
prevent rancidity the soap is boiled near the finish for 

79 



SOAP-MAKING MANUAL 

some time in the closed state with sufficient excess of 
alkali to give it a sharp taste, then grained with lye, 
the lye drawn off, closed with water and then grained 
with salt. This process is repeated until the desired 
strength is reached. The last graining should not be 
too great, and on the last change the soap should not 
be thinned out, as it will contain too great a quantity of 
water when slabbed. 

In making a cold castile soap the usual method is 
pursued as already directed under cold made soap. 
When the soap is taken from the crutcher it is ad- 
visable, however, to keep the soap in the frame well 
covered to assure complete saponification. Some manu- 
facturers use very small frames which are placed into 
compartments, well insulated to retain heat. Several 
formulae for cold made castile soaps, follow. It may 
be noted that some of these contain practically no olive oil. 

I 

Olive oil 2030 

Palm kernel 674 

Soda lye, 35 per cent. B 1506 

II 

Olive oil 2030 

Cochin cocoanut oil 674 

Soda lye, 36 per cent. B 1523 

Sodium Silicate 82 

III 

Palm kernel oil 1578 

Tallow 940 

Olive oil 7 

Sodium silicate, 20 per cent. B 190 

Soda lye, 36 per cent. B 1507 

80 



CLASSIFICATION OF SOAPS 

IV 

Olive oil (yellow) 1000 

Soda lye, Z7 per cent. B 500 

V 

Olive oil 90 

or 
Palm kernel . -^ 

Cochin or cocoanut oil 



4 

Lye, yj per cent. B 51 



If any of the soaps containing a high proportion of 
cocoanut oil are boiled the soap will float. It is there- 
fore necessary to keep the temperature as low as 
possible. 

ESCHWEGER SOAP (BLUE MOTTLED). 

Eschweger soap is a colored mottled or marbled soap 
made to a very slight extent in this country. Inasmuch 
as it has been introduced to the export trade, it is made 
for this purpose by some manufacturers. A high per- 
centage of cocoanut oil is usually used together with 
tallow and grease. About one-third of each is a typical 
formula. In a soap of this character the fact that 
cocoanut oil soap takes up a large quantity of water 
and salts of various kinds and is difficult to salt out is 
made use of. The tallow and grease are first saponified 
as usual, then the cocoanut oil is pumped and saponified. 
When the saponification is nearly completed either sili- 
cate or carbonate of soda or common salt are added to 
make the soap "short" so as to form the mottle. The 
finishing of a soap of this type can only be gained by 
practice and it is rather difficult to explain the exact 
appearance of the kettle at this stage. The surface of 
the soap should be bright and lustrous with the steam 

81 



SOAP-MAKING MANUAL 

escaping in numerous places in rose-like formation. A 
sample on the trowel should have a slight sharpness 
to the tongue and be pla^stic. When the soap slides 
from the trowel it should break short. When the soap 
has reached this stage the desired coloring matter, usually 
ultramarine, is added to the soap either in the kettle or 
crutcher and the soap framed. The yield is 200-215 pounds 
per hundred pounds of stock. 

Several modifications of this general method for 
Eschweger soap are used by adopting the half boiled 
or cold process. 

Transparent Soap. 

Transparent soap is really not a most desirable soap for 
toilet purposes, as it contains an excess of free alkali. It 
has, nevertheless, met with public approval because of the 
fact it is novel in being transparent. Except for this fact 
very little merit can be claimed for a soap of this kind. 

The transparency of soap is generally due to the presence 
of alcohol, sugar or glycerine in the soap when it is made 
It is very essential in a soap of this character, where light- 
ness and clearness of color are desired, that the material 
for making the soap be carefully selected as to color and 
purity. The perfumes also play an important part in the 
color of the soap and many of the tinctures, balsams and 
infusions used in perfuming soap may eventually cause 
trouble by spotting. If the soap is artificially colored, which 
is almost always the case, the dyestuffs used for this 
purpose should have careful attention and only those should 
be used which are known to resist the action of alkalis. 
Where rosin is used this product must be of the better 
grade. Distilled water is always preferable for use in trans- 
parent soap. The government permits the use of a specially 
denatured alcohol. This alcohol is not taxed and consists of 
grain (ethyl) alcohol denatured with 5 per cent, wood 

82 



CLASSIFICATION OF SOAPS 

(methyl) alcohol. Some soapmakers prefer to use a more 
expensive refined methyl alcohol, but outside of adding 
to the cost of the soap, there is no particular advantage. 
The glycerine should be chemically pure. As to the oils 
and fats these should be low in acid and of good color. 
Under no circumstances should the crutcher or kettle in 
which the soap is made be rusty or unclean in any way. 
For a light soap enameled utensils are to be preferred; 
To obtain transparency in soap the following general 
methods may be given. 

1. Where the transparency is due to sugar. 

2. Where alcohol and glycerine produce transparency. 

3. Where (1) or (2) is supplemented by the use of 
castor oil. 

4. Where transparency depends upon the percentage of 
fatty acid in a soap and the number of times the soap is 
milled. 

Under the first method at least 25 per cent, of the charge 
should be cocoanut oil, the other constituent being tallow 
or any fat or oil capable of giving a sufficiently hard soap. 
The soap is boiled and finished as usual, then run to the 
crutcher to be mixed with a strong cane sugar solution, 
containing 10-20 per cent, sugar of the weight of the soap. 
The sugar is dissolved in its own weight of water and the 
solution heated to 175 degs. F. before being very slowly 
added to the soap. As the water evaporates, soaps of this 
type show spots due to the sugar thus being thrown out 
of solution. 

Transparent soap made under the second method may 
be saponified as usual and consist of any good toilet base. 
The soap is run to the crutcher and mixed with 95 per cent, 
alcohol in the proportion of one part alcohol to two parts 
of fatty acid contained in the soap together with glycerine 
in the same proportion. 

83 



SOAP-MAKING MANUAL 

By the third method castor oil alone may be used to 
make the soap or added to any of the above bases up to 
33}i per cent, of the charge. If castor oil only is used, 
but 2 per cent, or 3 per cent, of sugar is required. 

In the last method a combination of 80 per cent, tallow, 
very low in free acid, 20 per Cent, cocoanut oil and 5 per 
cent. W. W. rosin is a suitable charge. The saponification 
and finishing is carried out as with a full boiled soap. 
The soap is then placed into a jacketed vessel, provided 
with dry-steam coils, by which the excess water is 
evaporated from the soap until it contains 73 per cent, fatty 
acids. When the thick mass reaches this stage it is framed 
and when cool is suitable for obtaining a semi transparency 
which now depends upon the number of times the soap is 
milled, it being, of course, inferred that no solid matter 
of any sort be added to the soap. 

Cold Made Transparent Soap. 

While transparent soaps may be made by the above 
general methods they are usually made by the semi-boiled 
or cold process. By this process a more satisfactory soap 
is obtained and it is more simple to carry out. A detailed 
description of this method is best and most easily given 
by using a typical formula. 

Charge : 

Tallow 193>^ lbs. 

Cochin Cocoanut Oil 169J^ 

Castor Oil 89>^ " 

Soda Ash 7H " 

Soda Lye, 36 degs. B 256 

Sugar (Cane) 198 " 

Alcohol 126 

Water (Distilled) 80- " 

84 



CLASSIFICATION OF SOAPS 

To proceed, first place into a crutcher or jacketed kettle 
the oils and fat and heat to 140 degs. F. Then add the 
soda ash dissolved in about 30 pounds of the water, after 
which the lye is added and the mass stirred until a finger 
or stick run over the surface leaves an imprint. Where 
the soap has reached this stage, it is well covered and 
allowed to stand about two hours or until it bulges in the 
center, after which the rest of the water which should 
contain no lime or other mineral substance and which is 
preferably distilled water, is added. The sugar is then 
slowly shoveled in while the mass is stirring and finally 
the alcohol is poured in. The heat is then increased to 
160 degs. F. by dry steam and the soap crutched until 
dissolved. Under no circumstances should any soap be 
allowed to remain above the surface of the mass on the 
sides of the mixer. This crutching operation consumes 
about one hour, and when finished the soap should stand 
in the vessel about half an hour when a small sample is 
taken out to cool. This sample should be clear and show 
an excess of alkali. If it is not clear more alcohol is^ 
added, if not of sufficient strength more lye put in until the 
desired condition is reached. The perfume and color are 
now added. 

The soap is then framed and allowed to set after which 
it is cut, allowed to dry slightly and then pressed. To 
obtain a polished cake transparent soaps are often planed 
before pressing and after pressing polished with a soft cloth, 
dampened with alcohol. Instead of framing this soap, it is 
sometimes "tubed," that is to say, the soap from the crutcher 
is run into specially constructed tubes of a shape near 
that of the desired cake and allowed to cool, after which 
it is cut and pressed. All scraps arc returned to the 
crutcher, but in so doing the soap is slightly darkened in 
color. It is advisable to expose a finished cake of trans- 

85 



SOAP-MAKING MANUAL 



parent soap to the air for some time as by so doing it 
becomes clearer. 

Other formulae for cold made transparent soaps made 
as just outlined follow: 

I. 

Bleached Tallow 134 lbs. 

Cochin Cocoanut Oil 88 

Castor Oil 20 

W. W. Rosin 7 

Cane Sugar 64 

Water 32 

Glycerine 34 

Soda Lye, 38 degs. B 135 

Alcohol 16 gal. 

IL 

Tallow 211 lbs. 

Cochin Cocoanut Oil 185 

Castor Oil 97j4 

Soda Ash 8^ 

Water 106 

Soda Lye, 38 degs. B 279 

Sugar 216 

Alcohol 137 



(( 



(( 



(( 



(( 



u 



ii 



u 



III. 

Castor Oil 60 

Cochin Cocoanut Oil 195 

Tallow 120 

Alcohol 115 

Sugar 90 

Water 53 

Glycerine 53 

Soda Lye, 38 degs. B 205^ 

86 



lbs. 



\ 



It 



CLASSIFICATION OF SOAPS 



IV. 

I Tallow 100 lbs. 

I Cochin Cocoanut Oil 100 " 

: Castor Oil 60 

i Glycerine 20 

Rosin, W. W 20 

Sugar 40 

Water 50 " 

Soda Lye, 36 degs. B 164 

Alcohol 8 gal. 

V. 

Tallow 174 lbs. 

Cocoanut Oil 114 " 

Soda Lye, 38 degs. B 170 " 

Sugar 80 " 

Water 72 " 

Alcohol 16 gal. 

Rosin may be added in this formula up to 20 per cent, 
of fats used and the tallow cut down correspondingly. 

SHAVING SOAPS. 

The requirements of a shaving soap are somewhat 
different than those of other soaps. To be a good shaving 
soap the lather produced therefrom must be heavy, creamy, 
but not gummy, and remain moist when formed on the 
face. The soap itself should be of a soft consistency so 
as to readily adhere to the face when used in stick form. 
It should furthermore be neutral or nearly so to prevent 
the alkali from smarting during shaving. 

Shaving soap is made in the form of a stick, and a tablet 
for use in the shaving mug. Some shavers prefer to have 
the soap as a powder or cream, which are claimed to be 
more convenient methods of shaving. While a liquid 
shaving soap is not as well known because it has not yet 

87 



SOAP-MAKING MANUAL 

become popular, some soap for shaving is made in this 
form. 

Formerly shaving soap was extensively made from a 
charge of about 80 parts tallow and 20 parts cocoanut oil 
as a boiled settled soap, but either making the strengthen- 
ing change with potash lye or using potash lye in saponify- 
ing the stock and graining with salt. Soaps for shaving 
made in this manner are very unsatisfactory, as they do 
not produce a sufficiently thick or lasting lather and dis- 
color very materially upon ageing. Potassium stearate 
forms an ideal lather for shaving, but readily hardens and 
hence needs some of the softer oils, or glycerine incor- 
porated with it to form a satisfactory soap for shaving. 

The selection of materials for making a shaving soap 
is important. The tallow used should be white and of 
high titer. Cochin cocoanut oil is to be preferred to the 
other kinds, and the alkalis should be the best for tech- 
nical use that can be purchased — 76 per cent, caustic soda 
and 88-92 per cent, caustic potash are suitable. By the use 
of stearic acid it is a simple matter to reach the neutral 
point which can be carefully approximated. 

The following are shaving soap formulae which have 
been found to give good satisfaction: 

I. lbs. 

Tallow 360 

Stearic acid 40 

Soda lye, 4V B •. . . 147 

Potash lye, 34' B 87 

Water 32 

Gum tragacanth 1 

II. lbs. 

Tallow 282 

Cocoanut oil 60 

88 



x^ 



CLASSIFICATION OF SOAPS 

Stearic acid 50 

Bayberry wax 18 

Soda lye, 4^6 147 

Potash lye, 34' B 90 

Water 32 

III. lbs. 

Tallow 400 

Cocoanut oil 176 

Stearic acid 415 

Caustic soda, 40' B 182 

Caustic potash, 38' B 108 

To proceed, first run into the crutcher the tallow, cocoa- 
nut oil and bayberry wax when used, and bring the tem- 
perature of the mass up to 140°-160' F. by dry steam. Then 
add the caustic soda lye and keep on heat with occasional 
mixing until it is all taken up. When this stage is reached 
gradually add all but about 5 per cent, of the potash lye, 
and complete the saponification. This point having been 
reached, the heat is turned off; the crutcher is run and 
the stearic acid, previously melted by dry steam in a lead- 
lined or enameled vessel, is run in in a continuous stream 
and the crutching continued for fifteen minutes to half 
an hour. Samples are taken at this time, cooled and 
tested by alcoholic phenolphthalein solution. If too alkaline 
more stearic acid is added, if too acid more potash lye 
from that previously reserved. After each addition of lye 
or stearic acid the mass is crutched from 10 to 15 minutes 
longer, another sample is taken, cooled and again tested. 
When the phenolphthalein shows a very light pink after 
several minutes, the soap is practically neutral, although 
at this point one can better judge by dissolving a sample 
in hot neutralized alcohol made by putting into the alcohol 
a few drops of phenolphthalein, and then adding weak 

89 



SOAP-MAKING MANUAL 

alkali drop by drop from a burette until a slight pink, not 
yellow, tint is obtained, and noting the color of the solu- 
tion. The solution should show a very light pink when 
the soap is properly neutralized. When this stage is ar- 
rived at the gum tragacanth, previously softened in water, 
is crutched in if it is to be added. The soap is then 
framed, stripped in three or four days, dried and milled. 
The formulae as given are for shaving sticks, and do 
not readily press unless thoroughly dried. A more satis- 
factory result is obtained by adding at the mill 25 per 
cent, of white tallow base to obtain a satisfactory mug 
soap. 

SHAVING POWDER. 

Shaving powder differs from the soaps just described 
in being pulverized, usually adding up to 5 per cent, starch 
to prevent caking. Any of the above soaps, dried bone 
dry, with or without the addition of tallow base make a 
satisfactory powder for shaving. 

SHAVING CREAM. 

Shaving cream is now a very popular shaving medium 
due to the rapidity and convenience with which one can 
shave by the use of this product. Formerly shaving 
cream was made from the liquid oils like olive oil and a 
soft fat Hke lard, together with cocoanut oil. Now, how- 
ever, most of the popular shaving creams are made from 
stearic acid and cocoanut oil, as a far superior product is 
obtained by the use of these substances. By using these a 
more satisfactory cream is obtained, and it is far more 
convenient to make. The lather also produced therefrom 
is more suitable for shaving, being thick, creamy and re- 
maining moist. 

A few typical formulae for shaving creams of this type 
are as follows: 

to 



CLASSIFICATION OF SOAPS 

I- lbs. 

Cochin cocoanut oil..'. 26 

Stearic acid 165 

Caustic potash lye, 50** B 69 

Glycerine C. P 76 

Water 38 

II- lbs. 

Cochin cocoanut oil 18 

Stearic acid 73 

Caustic potash lye, 39** B 54 

Glycerine 33 

Water 27 

"I- lbs. 

Cochin cocoanut oil 18 

Stearic acid 73 

Caustic potash lye, 39** B 54 

Glycerine 20 

Water 40 

and lbs. 

Stearic acid 60 

Glycerine C. P 85 

Water 165 

Sodium carbonate 50 

Borax 1 

To make a shaving cream by Formula I or II, the cocoa- 
nut oil and glycerine are first put into a suitable mixing 
apparatus or crutcher, and heated to 120® F. A part or 
all the potash lye is then added and the cocoanut oil 

fl 



w^ 



SOAP-MAKING MANUAL 

saponified. The rest of the potash lye and the water are 
then added, and with the mixer running the stearic acid, 
previously melted in a lead-lined or enameled vessel, is 
then poured in in a stream and the mass stirred until 
smooth, care being exercised not to aerate it too much. 
The cream is then tested for alkalinity, the best -method 
being by that described under shaving soap, in which 
the sample is dissolved in alcohol. Because of the large 
quantity of water present, phenolphthalein is unsatisfac- 
tory, as dissociation of the soap may show a pink indica- 
tion in spite of the fact the mass is on the acid side. For 
a quick method of testing the bite on the tongue is a 
satisfactory criterion. If a cooled sample bites the tongue 
more stearic acid is added until there is a 3% excess of this. 
When the proper neutralization has taken place the cream 
is perfumed and framed in a special frame, or it may be 
allowed to cool in the mixer and perfumed the next day. 
When cool the cream is strained, or put through an oint- 
ment mill, after which it is ready to fill into tubes. 

The procedure for the first part of Formula III is the 
same as that just given. The second part of the formula 
is made the same as a vanishing cream for toilet purposes. 
To make this, first melt the stearic acid as already directed. 
Dissolve the sodium carbonate and borax in water and 
when dissolved add the glycerine and stir. Then heat 
this solution to about 100" -120** F. and while stirring in 
a suitable mixing machine into which this solution has 
been poured after being heated, or better still in which 
it has . been heated by dry steam, add the stearic acid. 
Continue mixing until smooth and then allow to cool, or 
run into frames to cool. 

When the shaving cream and vanishing cream are both 
cool, they are mixed in the propcJrtion of one of the 
former to two of the latter. It is claimed that in thus 

^2 



CLASSIFICATION OF SOAPS 

making a shaving cream a smoother product is ob- 
tained, although it may be said that the vanishing cream 
is merely a soft soap and the ultimate result is the same 
as though the various ingredients were added in one 
operation, rather than making two separate products and 
then mixing them, thereby considerably increasing the cost 
of manufacture. 

PUMICE OR SAND SOAPS. 

Pumice and sand are at times added to soap to aid in 
the removal ol dirt in cleansing the hands. In some cases 
these soaps are made in the form of a cake, in others 
they are sold in cans in the form of a paste. 

A hand paste is usually made by merely dissolving 
ordinary tallow base in two or three times its weight of 
hot water and mixing in the desired quantity of pumice 
or sand and in some instances adding a little glycerine 
to keep it soft or a solvent of some kind for grease. It 
may also be made by directly incorporating any of these 
in a potash soap. 

A cold made or semi-boiled cocoanut or palm kernel oil 
soap is the base used to add the pumice or sand to in 
making a cake soap of this sort. The following formulae 
serve as a guide for these soaps. 

I. 

Palm Kernel or Ceylon Cocoanut Oil 705 lbs. 

Pumice (Powdered) 281 " 

Soda Lye, 38** B 378 " 



n. 

Cocoanut Oil 100 " 

Soda Lye, 38" B 55 " 

Water 6 " 

Silver Sand (fine) 60 ** 

93 



SOAP-MAKING MANUAL 

To proceed place the oil in a crutcher and heat to 140* 
F. Sift in the pumice and mix thoroughly. The lye is 
then added which causes a curdling of the grain. The 
stirring is continued until the grain closes and the soap 
is smooth, after which the desired perfume is added and 
the soap dropped into a frame and crutched by hand. 
When the soap is set, it is slabbed, cut into cakes, dried 
slightly and pressed. 

LIQUID SOAPS. 

Liquid soaps are merely solutions of a potash soap, 
usually cocoanut oil soap, although corn oil is used to 
make a cheap soap. One of the difficulties encountered 
in liquid soap is to keep it clear. At a low temperature 
a sediment is often formed, but this can be overcome by 
the use of sugar and filtering the soap through a filter 
press at a low temperature. In order to prevent the soap 
from freezing, it is necessary to lower the freezing point 
by the addition of glycerine or alcohol. 

To make liquid soap by any of the formulae given 
below, the oil is first run into a jacketed kettle with a 
stirring device, and heated to about 120* F. The potash 
lye is then added and the oil saponified. When the saponifi- 
cation takes place, especially when cocoanut oil is used, 
the mass swells rapidly and may foam over the sides of 
the kettle unless water is used to check this, or a kettle 
of about four to five times the capacity of the total charge 
of soap is used. When the saponification has occurred, 
the sugar, borax and glycerine are added, the water run 
in and the mixture stirred until the soap is thoroughly 
dissolved. Heat aids materially in dissolving the soap. 
The soap is then allowed to cool and if color or perfume 
is to be added this is stirred in, after which the soap is 
cooled and filtered or else run directly into barrels. 

94 



^ 



CLASSIFICATION OF SOAPS 






Tallow is not suitable for making a clear liquid soap 
since it is too high in stearine which when formed into 
the stearate makes an opaque solution. The formulae 
herewith given have been found to give good practical 
results. 

I. lbs. 

Cocoanut oil 130 

Caustic potash lye, 28* B. 135 

Sugar 72 

Borax 2 

Water 267 

n. lbs. 

Corn oil 130 

Caustic potash lye, 26** B 135 

Sugar 72 

Borax 2 

Water 267 

ni. lbs. 

Cocoanut oil 100 

Caustic potash lye, 28** B 102 

Glycerine 100 

Sugar 70 

Water 833 

Formulae I and II contain about 20 per cent, fatty acids. 
It is possible, of course, to either increase or decrease 
the percentage of fatty acid by varying the amount of 
water. The water used in making liquid soaps, of course, 
should be soft, for hard water forms insoluble soaps 
which precipitate and cause a sediment. 

95 



SOAP-MAKING MANUAL 

USE OF HARDENED OILS IN TOILET SOAPS. 

While the introduction of the hydrogenation of oils is a 
decided advance in the production of suitable cheaper oils 
for soap making, comparatively little hardened oil is em- 
ployed for soap making in America up to the present time. 
In Europe, however, considerable advance has been made 
by the use of such oils for manufacturing soap therefrom 
and a number of plants turn out large quantities of hydro- 
genated oils for soap making as well as for edible purposes. 
Recently a company has been formed in this country for 
hardening oils and it is very probable that the future will 
see this material extensively used in our own country, as 
these appear to be the one present hope of the soap manu- 
facturer as a check on the ever increasing cost of fats and 
oils now used in making soap. 

It is an unfortunate condition that hydrogenated oils 
produced abroad are sold under names which give ab- 
solutely no indication as to the oil which has been hardened. 
The softer and cheaper oils like fish oil, linseed oil, cotton- 
seed oil, etc., are generally hardened for soap manufacture 
to different degrees of hardness. While it is impossible to 
definitely state just what products as Candelite, Talgol, 
Krutolin or several other coined names of hardened oils 
are, various investigators have experimented with them as 
to their adaptability for producing toilet soaps and found 
that suitable toilet soaps may be made from them. While 
many objections were at first met with concerning soaps 
made from these products, as to their unsatisfactory saponi- 
fication, the poor lathering quality of the soaps and their 
odor and consequent difficulty in perfuming, the results of 
most investigators along these lines indicate that these in 
many cases were due to prejudice against or unfamiliarity 
with handling oils of this type for soap making. 

In manufacturing soap from hardened oils it is usually 

96 



"^ 



CLASSIFICATION OF SOAPS 

necessary to incorporate with the charge lard, tallow, tallow 
oil or some other soft oil of this nature. Satisfactory bases 
for toilet soaps, made as boiled settled soap by the use of 
Talgol (undoubtedly hardened fish oil), are said to be 
made by the formulae* below. 

I. 

Tallow 45 parts 

Talgol 40 " 

Cocoanut Oil 15 " 

II. 

Cocoanut Oil (Ceylon) 6 " 

Tallow 12 " 

Talgol, Extra 12 " 

The method of boiling a soap of this type does not differ 
materially from that of making settled tallow soap base. 
The soap itself has a different odor than a straight tallow 
base, but is said to make a very satisfactory soap for 
milling ^nd to be of good appearance. 

Satisfactory transparent soaps are made from the 
hardened oil Candelite, which replaces the tallow in trans- 
parent soap formulae such as have already been given in 
the section under "Transparent Soaps." The method of 
manufacturing a soap by the use of this product varies in 
no way from the usual method employed for making these 
soaps. 

Since hydrogenated oils are high in stearine, their use 
in shaving soaps is a decided advantage. It has pre- 
viously been pointed out that potassium stearate forms 
an ideal lather for shaving, and in the hydrogenating 
process the olein is converted to stearine. Thus a hardened 

•Seifcnsicdcr Ztg. (1913), p. 334 and 338. 

" " (1912), p. 1229 and 1257. 



9 



/ 



SOAP-MAKING MANUAL 

oil is advantageous in a shaving soap. As an example of 
a cold made soap for shaving the following may be taken.t 

Talgol Extra 50 lbs. 

Cocoanut Oil 10 " 

Lard 10 " 

Soda Lye, 38° B 20 " 

Potash Lye, 37** B 21 " 

This soap may be made in a crutcher by the method 
generally used in making soap by the cold process. 

TEXTILE SOAPS. 

Soap is a very important product to every branch of the 
textile industry. For woolen fabrics it is used for scouring, 
fulling and throwing the wool; in the silk industry it is 
necessary for degumming the raw silk, as well as for dye- 
ing; in the cotton mills it is used to finish cotton cloth 
and to some extent in bleaching; it is, furthermore, em- 
ployed in a number of ways in the manufacture of linen. 
Large quantities of soap are thus consumed in an in- 
dustry of so great an extent and the requirements neces- 
sitate different soaps for the different operations. We 
will, therefore, consider these in detail. 

SCOURING AND FULLING SOAPS FOR WOOL. 

The soaps used to scour wool and for fulling the woven 
cloth are usually made as cheaply as possible. They are, 
however, generally pure soaps, as filling material such as 
sodium silicate does not readily rinse out of the wool and 
if used at all must be added very sparingly. Both cold 
made and boiled settled soaps are made for this purpose. 
The soap is generally sold in barrels, hence is run directly 
to these from the crutcher or soap kettle. As cold made 
soaps the following serve for wool scouring or fulling. 

tSeifeniieder Ztr (1912), p. 954. 

98 



CLASSIFICATION OF SOAPS 

I. 

Palm Oil 200 lbs. 

Bone Grease 460 " 

Soda Lye, 36° B 357 " 

Water -. 113 " 

Soda Ash 50 " 

Citronella 2 " 

XL 

Palm Oil (Calabar, unbleached) 155 " 

House Grease 360 " 

Soda Lye, 36* B 324 " 

Water 268 " 

Sodium Silicate 83 " 

in. 

House Grease 185 " 

Palm Oil (unbleached) 309 

Soda Lye, 36* B 309 

Water 391 " 

Soda Ash 70 " 

Sodium Silicate 60 " 

Com Starch 10 " 

These soaps are made in a crutcher by the usual pro- 
cess for cold-made soaps, crutched until smooth, dropped 
into a barrel and crutched by hand the next day or just 
before cooling. 

As a settled soap for these operations the following 
charge is typical: 

Palm Oil 34 parts 

Cottonseed foots or its equivalent in 

fatty acids 33 " 

Rosin 10 " 

House Grease 23 

99 



ft 



SOAP-MAKING MANUAL 

The method of boiling such a soap is the same as for 
any settled soap up to the strengthening change. When 
this stage is reached, sufficient lye is added to strengthen 
the kettle strongly. It is then boiled down with closed 
steam on salt brine or "pickle" until a sample of the lye 
taken from the bottom stands at 16** -22° B. The soap is 
then run into barrels and after standing therein for a day 
is hand crutched until cool to prevent streaking of the soap. 

Besides a soap of this type a settled tallow chip soap is 
used. 

WOOL thrower's soap. 

Soaps for wool throwing are sometimes made from 
olive oil foots but these are often objected to because 
of the sulphur-like odor conveyed to the cloth due to the 
method by which this oil is extracted with carbon disul- 
phide. A potash soap hardened somewhat with soda is 
also used. As a formula for a suitable soap of this type 
this may be given. 

Olive Oil Foots 12 parts 

Corn Oil 46 " 

House Grease 20 " 

Soda Lye, 36** B 3 " 

Potassium Carbonate (dry) 5}i " 

Potassium Hydrate (solid) 23 " 

This soap is made as a "run" soap by the general 
directions already given for a soap thus made. The kettle 
is boiled with open and closed steam, adding water verj 
slowly and aiming to obtain a 220-225 per cent, yield ot 
fatty acid content of the finished soap of 46 per cent. 
When the soap is finished a sample cooled on a plate of 
glass should be neither slippery or short, but should string 
"jlightly. The finished soap is run directly into barrels. 

100 






CLASSIFICATION OF .• SOAPS 



«» « .• 



"> J J * * 



-* ^ 



r ^* 



A soap for wool throwing by the semi-boiled process 
may be made from olive oil foots in a crutcher thus : 

Olive Oil Foots 600 lbs. 

Potash Lye, 20** B 660 " 

The oil is heated to 180** F., the lye added and the 
mass stirred until it bunches, when it is dropped into 
barrels. 

WORSTED FINISHING SOAPS. 

For the finishing of worsted cloth soaps high in cocoa- 
nut oil or palm kernel oil are preferred. These soaps are 
finished very neutral, being made as settled soaps, but 
given an extra wash change after strengthening strongly. 
They are then finished as usual and run into barrels. If 
framed too hot, the high percentage of cocoanut oil 
causes mottling, which is prevented by crutching by hand 
until the temperature of the soap is 140*-145** F. Some 
typical charges, all of which are saponified with soda lye, 
follow : 

I. 

Palm Kernel Oil 60 parts 

Corn Oil 40 " 

IL 

Palm Kernel Oil 30 " 

Red Oil (single pressed) 70 " 

in. 

Red Oil 33J4 

Com Oil 3354 

Cocoanut Oil or Palm Kernel Oil 33 J^ 



(< 



t. 



>t 



SOAPS USED IN THE SILK INDUSTRY. 

Soap is used to a very large extent in silk mills, both for 

101 



• « 



SOAP-MAKING MANUAL 



degumtning the raw silk and in silk dyeing. Raw silk con- 
sists of the true silk fibre known as fibroin and a gummy 
coating, sericin, which dulls the lustre of the silk unless 
removed. For this purpose a slightly alkaline olive oil 
foots soap is best adapted, although palm oil and peanut 
oil soaps are sometimes used, as well as soaps made from 
a combination of house grease to the extent of 30 per 
cent., together with red oil or straight olein soaps, both 
of which are artificially colored green. In using house 
grease, if 30 per cent, is exceeded in combination with 
red oil, the titer is raised to such an extent that the 
soap does not readily rinse from the silk nor dissolve 
readily. They are also not advisable because they impart 
a disagreeable odor to the silk. 

To make a soap for this purpose from olive oil foots it 
is made as a settled soap, care being taken to thoroughly 
boil the mass on the saponification change in the closed 
state to assure proper saponification. The kettle is usually 
grained with lye and given a good wash change to remove 
the excess strength. The change previous to the finish 
should not be too heavy or too large a nigre results. The 
lighter the grain is, the better the finished kettle is. A 
yield of 150 per cent, is usually obtained. This soap is 
generally run to a frame, slabbed upon cooling and packed 
directly into wooden cases. 

For silk dyeing the above soap is suitable, although any 
well-made soap of good odor and not rancid is useable. 
While soap alone is often used in the bath for silk dyeing, 
certain dyestuffs require the addition of acetic or sulphuric 
acid, which sets free the fatty acids. If these be of bad 
odor it is taken up by the silk and is difficult to remove. 
The most generally used soaps are the just mentioned olive 
foots soap or a soap made from a good grade red oil. 

Both ki^ds are extensively used. 

102 



CLASSIFICATION OF SOAPS 

SOAPS USED FOR COTTON GOODS. 

In the manufacture of cotton goods, as compared to the 
wool and silk industries, very much less soap is used and 
it is only applied to the finished fabric either to clean the 
cloth preparatory to dyeing or to aid in dyeing with certain 
colors. It is also used in calico printing. For cleansing 
the cloth ordinary chip soap is suitable although a more 
alkaline soap finished as a curd soap is an advantage in 
that the free alkali contained therein aids in removing the 
dirt and has no harmful effect on the cotton. For dyeing 
cotton goods or to brighten certain colors after dyeing 
an olive oil foots soap is most generally employed. In 
calico printing soap is used to wash and clear the cloth 
after printing. A soap for this purpose should be easily 
soluble in water and contain no free alkali, rosin or filler. 
The best soaps for use in calico printing are either an olive 
oil foots soap or an olein soap. 

SULPHONATED OILS. 

While sulphonated oils are not use^ to any great extent 
in the manufacture of soap, they are used very largely in 
the dyeing and printing of turkey and alizarine reds on 
cotton as well as other colors. Just what action these oils 
have is not known. Turkey red oil or sulphonated castor 
oil is the best known sulphonated oil. 

The process of making these oils is simple. The equip- 
ment necessary is a wooden tank or barrel of suitable 
capacity, approximately two and a half times the amount 
of oil to be treated. There are furthermore required 
other tanks or vessels to hold the solutions used such as 
caustic soda, ammonia and acid. The tank to be used for 
the preparation of sulphonated oil should be provided 
with a valve at the bottom of the tank and a gauge to 
measure the quantity of liquid therein. 

103 



SOAP-MAKING MANUAL 

The process is carried out as follows: 

Three hundred pounds of castor oil are placed in the 
tank and 80 pounds at 66 deg. B. sulphuric acid are 
weighed out in another vessel. The acid is run into 
the tank containing the oil in a very thin stream while 
the oil is well stirred. At no time should the temperature 
exceed 40 deg. C. This operation should consume at 
least an hour and stirring should be continued half an 
hour longer to insure the thorough mixing of the oil with 
the acid. The mass is then allowed to settle for 24 
hours, after which 40 gallons of water are added and the 
mixture stirred until it has a uniform creamy color indi- 
cating no dark streaks. This mixing process should be 
carefully carried out and when completed allowed to settle 
36 hours. At this point the mass will have separated into 
two layers, the lower layer consisting of a water solution 
of acid and the upper layer of oil. The former is run out 
through the valve located at the bottom of the tank. An- 
other wash may now be given or dispensed with as de- 
sired. In this wash the addition of salt or sodium sulphate 
at the rate of 1^ pounds per gallon of water is advisable. 
A 24 deg. B. caustic soda solution is prepared and added 
slowly to the acidified oil with constant stirring. The 
mass first turns creamy, then becomes streaked, increasing 
in streaks as the caustic solution is poured in, and finally 
becomes clear and transparent. Water is now added 
to bring the volume to 75 gallons. The oil is now milky 
in appearance, but the addition of a little more soda solu- 
tion restores the transparency. 

In some cases ammonia is used in addition to caustic 
soda in neutralizing the oil. Three-fourths of the amount 
of caustic soda required to complete the neutralization is 
first added and then the neutralization is completed with 
a one to one liquid ammonia and water solution. 

104 



J 



CHAPTER V 

Glycerine Recovery. 

The recovery of glycerine is very closely allied with the 
soap-making industry, because glycerine is the very valuable 
by-product obtained in the saponification of oils and fats. 
No soap plant is, therefore, fully equipped unless it has 
some method whereby the glycerine is recovered and the 
importance of recovering this product cannot be too strong- 
ly emphasized. 

It has already been pointed out that neutral fats or the 
glycerides are a combination of fatty acid with glycerine. 
These are split apart in the process of saponification. While 
by the term saponification as used in soap making it is in- 
ferred that this is the combination of caustic alkalis with 
the fatty acids to form soap, this term is by no means lim- 
ited to this method of saponification, as there are various 
other methods of saponifying a fat. The chemical defini- 
tion of saponification is the conversion of an ester, of which 
glycerides are merely a certain type, into an alcohol and 
an acid or a salt of this acid. Thus, if we use caustic 
alkali as our saponifying agent for a fat or oil, we obtain 
the sodium or potassium salt of the higher fatty acids or 
soap and the alcohol, glycerine. On the other hand, if we 
use a mineral acid as the saponifying agent, we obtain the 
fatty acids themselves in addition to glycerine. While the 
former is by far the most generally employed for making 
soap, other processes consist in saponifying the fats by 
some method other than caustic alkalis and then convert- 
ing the fatty acids into soap by either neutralizing them 
with sodium or potassium carbonate or hydrate. 

It is important to again point out here that fats and oils 

lOS 



SOAP-MAKING MANUAL 

develop free fatty acid of themselves and that the devel- 
opment of this acid represents a loss in glycerine. The 
selection of an oil or fat for soap making should therefore 
to a large extent be judged as to its adaptability by the free 
fatty acid content, as the higher this content is, the greater 
is the loss in the glycerine eventually obtained. Glycerine 
often represents the only profit to a soap manufacturer. 
It is indeed necessary to determine the percentage of 
free fatty acid before purchasing a lot of stock to be made 
into soap. 

In taking up the question of glycerine recovery we will 
consider the various methods thus: 

1. Where * the glycerine is obtained from spent lye by 
saponifying the fats or oils with caustic alkali. 

2. Where the glycerine is obtained by saponifying the 
fats or oils by some other method than the above, of which 
there are the following: 

(a) Twitchell process. 

(b) Saponification by lime in autoclave. 

(c) Saponification by acid. 

(d) Saponification by water in autoclave. 

(e) Fermentative (Enzyms) 

(f) Krebitz process. 

RECOVERY OF GLYCERINE FROM SPENT LYE. 

The spent lye obtained from the glycerine changes in 
making soap varies greatly, the quality depending upon the 
stock saponified and the soap maker's care in handling the 
operation. No two lyes run exactly alike as to proportion 
of the various ingredients, although they are all similar 
in containing the same substances either in solution or 
suspension. Spent lye is a water solution of mainly glyc- 
erine, free alkali either as caustic alkali or carbonate and 
salt, including sodium sulfate, but furthermore contains 
some soap and albuminous matter either in solution or 

106 



GLYCERINE RECOVERY 

suspension. Upon standing in the storage tank the greater 
part of the soap usually separates when the lye cools. In 
order to assure the greatest economical yield of glycerine 
by saponifying a fat with caustic soda it is necessary to 
obtain a proportion of three parts of water to every part 
of fat made into soap. Test runs have shown that this is 
the proper proportion and that it is not economical to 
greatly exceed this amount, and if a much less proportion 
is used the full yield of glycerine is not obtained. 

The spent lyes contain varying amounts of glycerine, 
the first change being richest in glycerine content, and this 
being reduced in the subsequent changes. If the lyes al- 
ways run high in glycerine it is an indication that it is not 
all being obtained. The usual percentage is from 0.5% to 
5% or even more, although the average is somewhere 
around 2% to 3%. The lye as it comes from the kettle 
should not contain any more than 0.5% to 0.6% of free 
alkali calculated as sodium carbonate, NajCOs. If the pro- 
portion is higher than this, it shows that the saponification 
has been conducted with too high a proportion of alkali, 
a condition which should be corrected in the kettle room. 
An excess of free alkali does not interfere to any great 
extent with the successful recovery of the glycerine, but 
is a waste of both alkali and the acid used in neutralizing 
this. It is, therefore, more economical to run a strong lye 
over fresh stock and neutralize the alkali thus, rather than 
treating the lye for glycerine recovery. 

Before the spent lye can be run into the evaporator it is 
necessary to remove the albuminous impurities and soap 
and to neutralize the excess alkali to between exactly neu- 
tral and 0.02% alkalinity. The lye should never be fed 
into the evaporator in the acid condition. 

In order to treat the spent lyes for evaporation, they arc 
first allowed to cool in the storage tank, after which any 

107 



SOAP-MAKING MANUAL 

soap which may have separated is skimmed off and re- 
turned to the soap kettle. This lye is then pumped to the 
treatment tank, an ordinary tank equipped with some 
method of agitating the liquor, either by a mechanical 
stirrer, steam blower or compressed air, until it is about 
two feet from the top. 

After the lye has been skimmed off it is thoroughly 
agitated and a sample taken. The amount of lye in the 
tank is then calculated. Spent lye is about 1.09 times 
heavier than water, or weighs about 9 pounds to the gallon. 
While the sample is being tested for alkalinity it is advis- 
able to add sulfate of alumina, which may be dissolving 
while the sample is being titrated. This substance should 
be added in the proportion of anywhere from 6 to 14 
pounds per thousand pounds of lye, depending upon the 
amount of impurities contained therein. For a clean lye 
six pounds per thousand is sufficient, but for an impure 
lye a greater quantity is necessary. The sulfate of 
alumina used should be free from arsenic and sulfides and 
should contain a minimum amount of grit (silica), as grit 
reduces the life of the pump valves. This may be esti- 
mated with sufficient accuracy by rubbing the filtered-off 
portions, insoluble in water between the fingers and a 
plate of glass. The object of adding the sulfate of alumina 
is to transform the soap contained in the lye into the in- 
soluble aluminum soaps, and at the same time to coagulate 
the albuminous impurities. It must be remembered that 
the sulfate of alumina is added only for the fresh lye put 
into the tank. Thus if there were 10,000 pounds of lye in 
the treating tank when the fresh lye was run in, and 50,000 
pounds when the tank is filled, adding nine pounds of 
sulfate of alumina per thousand of lye, only 360 pounds 
would be added or enough for 40,000 pounds. Sulfate of 
alumina neutralizes one-third of its weight of caustic. 

108 



GLYCERINE RECOVERY 

To determine the alkali in the sample, 10 cubic centime- 
ters are pipetted into a beaker, a little distilled water added, 
then 3 or 4 drops of phenolphthalein indicator. From a 
burette, quarter normal (N/4) sulfuric acid is added until 
the pink color is just discharged. When this point is 
reached 4 to 5 c. c. more of acid are added and the solution 
is boiled to expel the carbon dioxide. Should the solution 
turn pink, it is necessary to add more acid. After having 
boiled for 3 to 4 minutes, N/4 caustic soda is added until 
the pink color just returns and the amount of caustic soda 
used is read on the burette. The difference between the 
number of cubic centimeters of N/4 sulfuric acid and N/4 
caustic soda gives the amount of alkali in the sample. By 
using a 10 c. c. sample and N/4 sulfuric acid and N/4 
caustic soda each c. c. obtained by the difference of these 
two solutions is equal to one-tenth of one per cent. (0.1%) 
of the total alkali in the lye. As an example, say we first used 
7.7 c. c. of N/4 sulfuric acid to just discharge the pink, then 
added 4 c. c. more, or 11.7 c. c. in total. After boiling it re- 
quired 5.3 c. c. to bring back a slight pink, the total. alkalin- 
ity would be 11.7 c. c. — 5.3 c. c. = 6.4 c. c, or 0.64% total 
alkaU in the lye in terms of caustic soda. If there were 
40,000 pounds of lye to be treated then we should have to 
neutralize : 

40,000 X .0064 = 256 lbs. alkali. Since sulfate of alumina 
neutralizes one-third of its weight in caustic, and there are 
say 9 lbs. of this added per thousand pounds of lye we 
would add 

40,000 X 9 = 360 lbs. of sulfate of alumina. This would 
neutralize 

360 X H = 120 lbs of alkali. There are then 256 — 120 
= 136 lbs. of alkali still to be neutralized. If 60** B. sul- 
furic acid is used it requires about 1.54 lbs. of acid to one 
pound of caustic. Therefore to neutralize the caustic 
soda remaining it requires: 

109 



ryr 



SOAP-MAKING MANUAL 

136 X 1.54 = 209.44 lbs. 60** B. sulfuric acid to neutral- 
ize the total alkali in the 40,000 pounds of spent lye. 

The acid is added and the lye well stirred, after which 
another sample is taken and again titrated as before. From 
this titration the amount of acid to be added is again cal- 
culated and more acid is added if necessary. Should too 
much acid have been added, caustic soda solution is added 
until the lye is between exactly neutral and 0.02% alkaline. 
The filtered lyes at this stage have a slight yellowish cast. 

To be sure that the lyes are treated correctly the precipi- 
tation test is advisable. To carry this out filter about 50 
c. c. of the treated lye and divide into two portions in a 
test tube. To one portion add ammonia drop by drop. If 
a cloudiness develops upon shaking, more alkali is added 
to the lye in the tank. To the other portion add a few 
drops of 1 to 5 sulfuric acid and shake the test tube. If 
a precipitate develops or the solution clouds, more acid is 
needed. When the lyes are treated right no cloudiness 
should develop either upon adding ammonia or the di- 
lute acid. 

The properly treated lye is then run through the filter 
press while slightly warm and the filtered lye is fed to the 
evaporator from the filtered lye tank. The lye coming 
from the filter press should be clear and have a slight 
yellowish cast. As the pressure increases it is necessary to 
clean the press or some of the press cake will pass through 
the cloths. Where sodium silicate is used as a filler, the 
silicate scrap should never be returned to the soap kettle 
until the glycerine lyes have been withdrawn. This practice 
of some soapmakers is to be strongly censured, as it 
causes decided difficulty in filtering the lye, since during 
the treatment of the lye, free silicic acid in colloidal form is 
produced by the decomposition of the sodium silicate by 
acid. This often prevents filtering the treated lye even at 

110 



GLYCERINE RECOVERY 

excess pressure and at its best retards the filtering. 

As to the filter press cake, this may be best thrown away 
in a small factory. Where, however, the output of glycerine 
is very large it pays to recover both the fatty acids and 
alumina in the press cakes. 

In some cases, especially when the lyes are very dirty 
and the total residue in the crude glycerine runs high, for 
which there is a penalty usually attached, a double filtra- 
tration of the lye is advisable. This is carried out by first 
making the lye slightly acid in reaction by the addition 
of alum and acid, then filtering. This filtered lye is then 
neutralized to the proper point with caustic, as already 
described, and passed through the filter press again. 

While in the method of treating the lyes as given sul- 
furic acid is used for neutralizing, some operators prefer 
to use hydrochloric acid, as this forms sodium chloride or 
common salt, whereas sulfuric acid forms sodium sul- 
fate, having ^ the graining power of salt, which event- 
ually renders the salt useless for graining the soap, as the 
percentage of sodium sulfate increases in the salt. When 
the salt contains 25 per cent, sodium sulfate it is advisable 
to throw it away. Sulfuric acid, however, is considerably 
cheaper than hydrochloric and this more than compensates 
the necessity of having to eventually reject the recovered 
salt. It may here also be mentioned that recovered salt 
contains 5-7 per cent, glycerine which should be washed 
out in the evaporator before it is thrown away. The follow- 
ing tables give the approximate theoretical amounts of 
acids of various strengths required to neutralize one 
pound of caustic soda: 

For 1 pound of caustic soda — 
3.25 lbs. 18** B. hydrochloric (muriatic) acid are required. 



2.92 " 


20** B. 


It 


It 


a 


u 


u 


2.58 " 


22* B. 


tt 


u 


u 


tt 


tt 



111 



SOAP-MAKING MANUAL 

For 1 pound of caustic soda — 

1.93 lbs. 50° B. sulphuric acid are required. 
1.54 " 60** B. " " " 

1.28 " 66° B. " " " 

It is, of course, feasible to neutralize the spent lye with- 
out first determining the causticity by titrating a sample and 
this is often the case. The operator under such conditions 
first adds the sulfate of alumina, then the acid, using 
litmus paper as his indicator. Comparatively, this method 
of treatment is much slower and not as positive, as the 
amount of acid or alkali to be added is at all times un- 
certain, for in the foaming of the lyes their action on litmus 
is misleading^ 

After the lye has been filtered to the filtered lye tank i\ 
is fed to the evaporator, the method of operation of which 
varies somewhat with different styles or makes. When it 
first enters tKe evaporator the lye is about 11°-12° B. After 
boiling the density will gradually rise to 27° B. and remain 
at this gravity for some time and during which time most 
of the salt is dropped out in the salt filter. As the lye 
concentrates the gravity gradually rises to 28°-30° B., which 
is half crude glycerine and contains about 60 per cent, 
glycerine. Some operators carry the evaporation to this 
point and accumulate a quantity of half crude before going 
on to crude. After half crude is obtained the temperature 
on the evaporator increases, the vacuum increases and the 
pressure on the condensation drain goes up (using the same 
amount of live steam). As the liquor grows heavier the 
amount of evaporation is less, and less steam is required 
necessitating the regulation of the steam pressure on the 
drum. When a temperature of 210° F. on the evaporator, 
with 26 or more inches vacuum on the pump is arrived at, 
the crude stage has been reached and the liquor now con- 
tains about 80 per cent, glycerine in which shape it is 

112 



GLYCERINE RECOVERY 

usually sold by soap manufacturers. A greater concen- 
tration requires more intricate apparatus. After settling a 
day in the crude tank it is drummed. 

Crude glycerine (about 80 per cent, glycerol) free from 
salt is 33* B., or has a specific gravity of 1.3. A sample 
boiled in an open dish boils at a temperature of 155* C. 
or over. 

TWITCHELL PROCESS. 

The Twitchell process of saponification consists of caus- 
ing an almost complete cleavage of fats and oils by the use 
of the Twitchell reagent or saponifier, a sulfo-aromatic 
compound. This is made by the action of concentrated 
sulfuric acid upon a solution of oleic acid or stearic acid 
in an aromatic hydrocarbon. From 0.5 per cent, to 3 per 
cent, of the reagent is added and saponification takes place 
from 12-48 hours by heating in a current of live steam 
The reaction is usually accelerated by the presence of a few 
per cent, of free fatty acids as a starter. Recently the 
Twitchell double reagent has been introduced through 
which it is claimed that better colored fatty acids are ob- 
tained and the glycerine is free from ash. 

The advantages claimed for the Twitchell process as 
outlined by Joslin* are as follows : 

1. All the glycerine is separated from the stock before 
entering the kettle, preventing loss of glycerine in the soap 
and removing glycerine from spent lye. 

2. The liquors contain 15-20 per cent, glycerine whereas 
spent lyes contain but 3-5 per cent, necessitating less 
evaporation and consequently being more economical in 
steam, labor and time. 

3. No salt is obtained in the liquors which makes the 
evaporation cheaper and removes the cause of corrosion of 



>Journ. Ind. Enf. Chem. (1909), I, p. 654. 

113 



SOAP-MAKING MANUAL 

the evaporator; also saves the glycerine retained by the 
salt. 

4. The glycerine liquors are purer and thus the treatment 
of the lyes is cheaper and simpler and the evaporation 
less difficult. 

5. The glycerine can readily be evaporated to 90 per cent, 
crude rather than 80 per cent, crude, thus saving drums, 
labor in handling and freight. The glycerine furthermore 
receives a higher rating and price, being known as saponi- 
fication crude which develops no glycols in refining it. 

6. The fatty acids obtained by the Twitchell saponifier 
may be converted into soap by carbonates, thus saving 
cost in alkali. 

7. There is a decrease in the odor of many strong 
smelling stocks. 

8. The glycerine may be obtained from half boiled and 
cold made soaps as well as soft (potash) soaps. 

While the advantages thus outlined are of decided value 
in the employment of the Twitchell process, the one great 
disadvantage is that the fatty acids obtained are rather 
dark in color and are not satisfactorily employed for the 
making of a soap where whiteness of color is desired. 

To carry out the process the previously heated oil or 
fat to be saponified is run into a lead lined tank. As 
greases and tallow often contain impurities a preliminary 
treatment with sulfuric acid is necessary. For a grease 
1.25 per cent, of half water and half 66° B. sulfuric acid 
is the approximate amount. The undiluted 66* B. acid 
should never be added directly, as the grease would be 
charred by this. The grease should be agitated by steam 
after the required percentage of acid, calculated on the 
weight of the grease, has been added. The wash lye 
coming off should be 7**-10° B. on a good clean grease or 
IS** -22* B. on cotton oil or a poor grease. As has been 

114 



GLYCERINE RECOVERY 

stated the grease is heated before the acid is added or the 
condensation of the steam necessitates the addition of more 
acid. After having boiled for 1-2 hours the grease is 
allowed to settle for 12 hours and run off through a swivel 
pipe. 

After the grease has been washed, as just explained, 
and settled, it is pumped into a covered wooden tank con- 
taining an open brass coil. Some of the second lye from 
a previous run is usually left in this tank and the grease 
pumped into this. The amount of this lye should be about 
one-third to one-half the weight of the grease so that there 
is about 60 per cent, by weight of grease in the tank after 
24 hours boiling. Where occasions arise when there is no 
second lye about 50 per cent, by weight of distilled water 
to the amount of grease is run into the tank to replace the 
lye. The saponifier is then added through a glass or 
granite ware funnel after the contents of the tank have 
been brought to a boil. If the boiling is to be continued 
48 hours, 1 per cent, of saponifier is added. For 24 hours 
boiling add 1.5 per cent. The boiling is continued for 24-48 
hours allowing 18 inches for boiling room or the grease 
will boil over. 

After boiling has continued the required length of time 
the mass is settled and the glycerine water is drawn off to 
the treatment tank. Should a permanent emulsion have 
formed, due to adding too great an amount of saponifier, 
a little sulfuric acid (0.1 per cent.-0.3 per cent.) will 
readily break this. During the time this is being done the 
space between the grease and the cover on the tank is kept 
filled with steam as contact with the air darkens the fatty 
acids. 

To the grease remaining in the tank distilled water (con- 
densed water from steam coils) to one-half its volume is 
added and the boiling continued 12-24 hours. The grease 

lis 



SOAP-MAKING MANUAL 

is then settled and the clear grease run off through a 
swivel pipe. A layer of emulsion usually forms between 
the clear grease and lye so that it may easily be de- 
termined when the grease has all been run off. To pre- 
vent discoloration of the fatty acids it is necessary to 
neutralize the lye with barium carbonate. The amount of 
this to be added depends upon the percentage of saponifier 
used. About 1/10 the weight of saponifier is the right 
amount. The barium carbonate is added through the fun- 
nel at the top of the tank mixed with a little water and 
the lye tested until it is neutral to methyl orange indicator. 
When the fatty acids are thus treated they will not darken 
upon exposure to the air when run off. 

Fresh grease is now pumped into the lye or water re- 
maining in the tank and the process repeated. 

The glycerine water or first lye is run to the treatment 
tank, the fat skimmed off and neutralized with lime until it 
shows pink with phenolphthalein, after having been thor- 
oughly boiled with steam. About 0.25 per cent, lime is the 
proper amount to add. The mixture is then allowed to 
settle and the supernatant mixture drawn off and run to the 
glycerine evaporator feed tank. The lime which holds 
considerable glycerine is filtered and the liquor added to the 
other. The evaporation is carried out in two stages. The 
glycerine water is first evaporated to about 60 per cent, 
glycerol, then dropped into a settling tank to settle out the 
calcium sulfate. The clear liquor is then evaporated to 
crude (about 90 per cent, glycerine) and the sediment 
filtered and also evaporated to crude. 

As to the amount of saponifier to use on various stocks, 
this is best determined by experiment as to how high a 
percentage gives dark colored fatty acids. For good stock 
such as clean tallow, prime cottonseed oil, corn oil. 
cocoanut oil and stock of this kind 0.75 per cent, saponifier 

116 



GLYCERINE RECOVERY 

is sufficient. For poorer grades of tallow, house grease, 
poor cottonseed oil, etc., 1 per cent, saponifier is required 
and for poorer grade greases higher percentages. The 
percentage of fatty acids developed varies in various stocks, 
and also varies with the care that the operation is carried 
out, but is usually between 85 per cent. -95 per cent. Due 
to the water taken up in the saponification process there 
is a yield of about 103 pounds of fatty acids and glycerine 
for 100 pounds of fat. 

The Twitchell reagent has undoubtedly caused a decided 
advance in the saponification of fats and oils and has been 
of great value to the soap manufacturer, because wi^^h a 
small expenditure it is possible to compete with the much 
more expensive equipment necessary for autoclave sapon- 
ification. The drawback, however, has been that the 
reagent imparted a dark color to the fatty acids obtained, 
due to decomposition products forming when the reagent 
is made, and hence is not suitable for use in soaps where 
whiteness of color is desired. 

There have recently been two new reagents introduced 
which act as catalyzers in splitting fats, just as the Twitchell 
reagent acts, but the fatty acids produced by the cleavage 
are of good color. The saponification, furthermore, takes 
place more rapidly. These are the Pfeilring reagent and 
Kontact reagent. 

The Pfeilring reagent is very similar to the Twitchell 
reagent, being made from hydrogenated castor oil and 
naphthalene by sulfonation with concentrated sulfuric acid. 
It is manufactured in Germany and is being extensively 
used in that country with good success. 

The Kontact or Petroff reagent, discovered by Petroff in 
Russia, is made from sulfonated mineral oils. Until very 
recently it has only been manufactured in Europe, but now 
that it has been found possible to obtain the proper min- 

117 



SOAP-MAKING MANUAL 

eral constituent from American petroleum, it is being manu- 
factured in this country, and it is very probable that it will 
replace the Twitchell reagent because of the advantages 
derived by using it, as compared to the old Twitchell 
reagent. 

The method and equipment necessary for employing 
either the Pfeilring or Kontact reagents is exactly the 
same as in using the Twitchell process. 

AUTOCLAVE SAPONIFICATION. 

While the introduction of the Twitchell process to a 
great extent replaced the autoclave method of saponifica- 
tion for obtaining fatty acids for soap making, the auto- 
clave method is also used. This process consists in heat- 
ing the previously purified fat or oil in the presence of 
lime and water, or water only, for several hours, which 
causes a splitting of the glycerides into fatty acids and 
glycerine. The advantage of autoclave saponification over 
the Twitchell process is that a greater cleavage of the fats 
and oils results in less time and at a slightly less expense. 
The glycerine thus obtained is also purer and of better 
color than that obtained by Twitchelling the fats. 

An autoclave or digestor consists of a strongly construct- 
ed, closed cylindrical tank, usually made of copper, and is 
so built as to resist internal pressure. The digestor is 
usually 3 to 5 feet in diameter and from 18 to 25 feet high. 
It may be set up horizontally or vertically and is covered 
with an asbestos jacket to retain the heat. Various inlets 
and outlets for the fats, steam, etc., as well as a pressure 
gauge and safety valve are also a necessary part of the 
equipment. 

UME SAPONIFICATION. 

The saponification in an autoclave is usually carried out 
by introducing the fats into the autoclave with a percentage 

118 



GLYCERINE RECOVERY 

of lime, magnesia or zinc oxide, together with water. If 
the fats contain any great amount of impurities, it is first 
necessary to purify them either by a treatment with weak 
sulfuric acid, as described under the Twitchell process, or 
by boiling them up with brine and settling out the impuri- 
ties from the hot fat. 

To charge the autoclave a partial vacuum is created 
therein by condensation of steam just before running the 
purified oil in from an elevated tank. The required quan- 
tity of unslaked lime, 2 to 4 per cent, of the weight of the 
fat, is run in with the molten fat, together with 30 per 
cent, to 50 per cent, of water. While 8.7 per cent, lime is 
theoretically required, practice has shown that 2 per cent, 
to 4 per cent, is sufficient. The digestor, having been 
charged and adjusted, steam is turned on and a pressure 
of 8 to 10 atmospheres maintained thereon for a period of 
six to ten hours. Samples of the fat are taken at 
various intervals and the percentage of free fatty acids de- 
termined. When the saponification is completed the con- 
tents of the autoclave are removed, usually by blowing out 
the digestor into a wooden settling tank, or by first running 
off the glycerine water and then blowing out the lime, soap 
and fatty acids. The mass discharged from the digestor 
separates into two layers, the upper consisting of a mix- 
ture of lime soap or "rock" and fatty acids, and the lower 
layer contains the glycerine or "sweet" water. The glycer- 
ine water is first run off through a clearing tank or oil 
separator, if this has not been done directly from the auto- 
clave, and the mass remaining washed once or twice more 
with water to remove any glycerine still retained by the 
lime soap. The calculated amount of sulfuric acid to de- 
compose the lime "rock" is then added, and the mass agi- 
tated until the fatty acids contained therein are entirely 
set free. Another small wash is then given and the wash 

119 



SOAP-MAKING MANUAL 

water added to the glycerine water already run off. The 
glycerine water is neutralized with lime, filtered and con- 
centrated as in the Twitchell process. 

Due to the difficulties of working the autoclave saponifi- 
cation with lime, decomposing the large amount of lime 
soap obtained and dealing with much gypsum formed 
thereby which collects as a sediment and necessitates clean- 
ing the tanks, other substances are used to replace lime. 
Magnesia, about 2 per cent, of the weight of the fat, is used 
and gives better results than lime. One-half to 1 per cent, 
of zinc oxide of the weight of the fat is even better 
adapted and is now being extensively employed for this 
purpose. In using zinc oxide it is possible to recover the 
zinc salts and use them over again in the digestor, which 
makes the process as cheap to work as with lime, with far 
more satisfactory results. 

ACID SAPONIFICATION. 

While it is possible to saponify fats and oils in an auto- 
clave with the addition of acid to the fat, unless a specially- 
constructed digestor is built, the action of the acid on the 
metal from which the autoclave is constructed prohibits 
its use. The acid saponification is therefore carried out by 
another method. 

The method of procedure for acid saponification, there- 
fore, is to first purify the fats with dilute acid as alread> 
described. The purified, hot or warm, dry fat is then run 
to a specially-built acidifier or a lead-lined tank and from 
4 per cent, to 6 per cent, of concentrated sulfuric acid 
added to the fat, depending upon its character, the degree 
of saponification required, temperature and time of sapon- 
ification. A temperature of 110 degrees C. is maintained 
and the mass mixed from four to six hours. The tank is 
then allowed to settle out the tar formed during the sapon- 

120 



f 



GLYCERINE RECOVERY 

ification, and the fatty acids run off to another tank and 
boiled up about three times with one-third the amount of 
water. The water thus obtained contains the glycerine, 
and after neutralization is concentrated. 

AQUEOUS SAPONIFICATION. 

While lime or a similar substance is ordinarily used to 
aid in splitting fats in an autoclave, the old water process 
is still used. This is a convenient, though slower and 
more dangerous method, of producing the hydrolysis of 
the glyceride, as well as the simplest in that fatty acids 
and glycerine in a water solution are obtained. The method 
consists in merely charging the autoclave with fats and 
adding about 30 per cent, to 40 per cent, of their 
weight of water, depending on the amount of free 
fatty acid and subjecting the charge to a pres- 
sure of 150 to 300 pounds, until the splitting has 
taken place. This is a much higher pressure than when 
lime is used and therefore a very strong autoclave is re- 
quired. Since fatty acids and pure glycerine water are 
obtained no subsequent treatment of the finished charge is 
necessary except separating the glycerine water and giving 
the fatty acids a wash with water to remove all the 
glycerine from them. 

SPLITTING FATS WITH FERMENTS. 

In discussing the causes of rancidity of oils and fats it 
was pointed out that the initial splitting of these is due 
to enzymes, organized ferments. In the seeds of the 
castor oil plant, especially in the protoplasm of the seed, 
the enzyme which has the property of causing hydrolysis 
of the glycerides is found. The ferment from the seeds 
of the castor oil plant is now extracted and used upon a 
commercial basis for splitting fats. 

The equipment necessary to carry out this method of 

121 



SOAP-MAKING MANUAL 

saponification is a round, iron, lead-lined tank with a conical 
bottom, preferably about twice as long as it is wide. Open 
and closed steam coils are also necessary in the tank. 

The oils are first heated and run into this tank. The 
right temperature to heat these to is about 1 degree to 2 
degrees above their solidification point. For liquid oils 
23 degrees C. is the proper heat as under 20 degrees C. 
the cleavage takes place slowly. Fats titering 44 degrees 
C. or above must be brought down in titer by mixing 
with them oils of a lower titer as the ferment or enzyme 
IS killed at about 45 degrees C. and thus loses its power 
of splitting. It is also necessary to have the fat in the 
liquid state or the ferment does not act. The proper 
temperature must be maintained with dry steam. 

It is, of course, necessary to add water, which may be any 
kind desired, condensed, water from steam coils, well, city, 
etc. From 30 per cent, to 40 per cent., on the average 35 
per cent, of water is added, as the amount necessary is 
regulated so as to not dilute the glycerine water unneces- 
sarily. To increase the hydrolysis a catalyzer, some neu- 
tral salt, usually manganese sulfate is added in the propor- 
tion of 0.15 per cent, appears to vary directly as the 
saponification number of the fat or oil. The approximate 
percentages of fermentive substance to be added to various 
oils and fats follow: 

Cocoanut oil 8 % 

Palm Kernel oil 8 % 

Cottonseed oil 6-7 % 

Linseed oil 4-5 % 

Tallow oil 8-10% 

The oil, water, manganese sulfate and ferment having 
been placed in the tank in the order named, the mixture is 
agitated with air for about a quarter of an hour to form 

122 



GLYCERINE RECOVERY 

an even emulsion, in which state the mass is kept by stirring 
occasionally with air while the saponification is taking 
place. A temperature is maintained a degree or two above 
the titer point of the fat with closed steam which may 
be aided by covering the tank for a period of 24 to 48 
hours. The splitting takes place rapidly at first, then pro- 
ceeds more slowly. In 24 hours 80 per cent, of the fats are 
split and in 48 hours 85 per cent, to 90 per cent. 

When the cleavage has reached the desired point the 
mass is heated to 80 degrees-85 degrees C. with live or 
indirect steam while stirring with air. Then 0.1 per cent.- 
0.15 per cent of concentrated sulfuric acid diluted with 
water is added to break the emulsion. When the emulsion 
is broken the glycerine water is allowed to settle out and 
drawn off. The glycerine water contains 12 per cent, 
to 25 per cent, glycerine and contains manganese sulfate, 
sulfuric acid and albuminous matter. Through neutraliza- 
tion with lime at boiling temperature and filtration the 
impurities can almost all be removed after which the 
glycerine water may be fed to the evaporator. Should it be 
desired to overcome the trouble due to the gypsum formed 
in the glycerine, the lime treatment may be combined with 
a previous treatment of the glycerine water with barium 
hydrate to remove the sulfuric acid, then later oxalic acid 
to precipitate the lime. 

The fatty acids obtained by splitting with ferments are of 
very good color and adaptable for soap making. 

KREBITZ PROCESS. 

The Krebitz process which has been used to some extent 
in Europe is based upon the conversion of the fat or oil 
into lime soap which is transformed into the soda soap by 
the addition of sodium carbonate. To carry out the process 
a convenient batch of, say, 10,000 pounds of fat or oil, is run 
into a shallow kettle containing 1,200 to 1,400 pounds of lime 

123 



y^ 



SOAP-MAKING MANUAL 

previously slaked with 3,700 to 4,500 pounds of water. The 
mass is slowly heated with live steam to almost boiling 
until an emulsion is obtained. The tank is then covered 
and allowed to stand about 12 hours. The lime soap thus 
formed is dropped from the tank into the hopper of a 
mill, finely ground and conveyed to a leeching tank. The 
glycerine is washed out and the glycerine water run to a 
tank for evaporation. The soap is then further washed 
and these washings are run to other tanks to be used over 
again to wash a fresh batch of soap. About 150,000 pounds 
of water will wash the soap made from 10,000 poujnds of 
fat which makes between 15,000 and 16,000 pounds of soap. 
The first wash contains approximately 10 per cent, glycer- 
ine and under ordinary circumstances this only need be 
evaporated for glycerine recovery. 

After extracting the glycerine the soap is slowly intro- 
duced into a boiling solution of sodium carbonate or soda 
ash and boiled until the soda has replaced the lime. This 
fs indicated by the disappearance of the small lumps of 
lime soap. Caustic soda is then added to saponify the fat 
not converted by the lime saponification. The soap is then 
salted out and allowed to settle out the calcium carbonate. 
This drops to the bottom of the kettle as a heavy sludge 
entangling about 10 per cent, of the soap. A portion of 
this soap may be recovered by agitating the sludge with 
heat and water, pumping the soap off the top and filtering 
the remaining sludge. 

While the soap thus obtained is very good, the percent- 
age of glycerine recovered is greatly increased and the 
cost of alkali as carbonate is less. The disadvantages are 
many. Large quantities of lime are required; it is difficult 
to recover the soap from the lime sludge ; the operations are 
numerous prior to the soap making proper and rather com- 
plicated apparatus is required. 

124 



GLYCERINE RECOVERY 



DISTILLATION OF FATTY ACIDS. 



The fatty acids obtained by various methods of saponifi- 
cation may be further improved by distillation. 

In order to carry out this distillation, two methods may 
be pursued, first, the continuous method, whereby the 
fatty acids are continually distilled for five to six days, 
and, second, the two phase method, whereby the distilla- 
tion continues for 16 to 20 hours, after which the residue 
is drawn off, treated with acid, and its distillate added 
to a fresh charge of fatty acids. The latter method is by 
far the best, since the advantages derived by thus pro- 
ceeding more^than compensate the necessity of cleaning 
the still. Better colored fatty acids are obtained; less 
unsaponifiable matter is contained therein; there is no 
accumulation of impurities; the amount of neutral fat 
is lessened because the treatment of the tar with acid 
causes a cleavage of the neutral fat and the candle tar or 
pitch obtained is harder and better and thus more valu- 
able. 

The stills are usually built of copper, which are heated by 
both direct fire and superheated steam. Distillation under 
vacuum is advisable. To begin the distilling operation, the 
still is first filled with dry hot fatty acids to the proper 
level. Superheated steam is then admitted and the con- 
denser is first heated to prevent the freezing of the fatty 
acids, passing over into same. When the temperature 
reaches 230 deg. C. the distillation begins. At the begin- 
ning, the fatty acids flow from the condenser, an intense 
green color, due to the formation of copper soaps produced 
by the action of the fatty acids on the copper still. This 
color may easily be removed by treating with dilute acid 
to decompose the copper soaps. 

In vacuum distillation, the operation is begun without 

125 



SOAP-MAKING MANUAL 

the use of vacuum. Vacuum is introduced only when the 
distillation has proceeded for a time and the introduction 
of this must be carefully regulated, else the rapid influence 
of vacuum will cause the contents of the still to overflow. 
When distillation has begun a constant level of fatty acids 
is retained therein by opening the feeding valve to same, 
and the heat is so regulated as to produce the desired rate 
of distillation. As soon as the distillate flows darker and 
slower, the feeding valve to the still is shut off and the 
distillation continued until most of the contents of the still 
are distilled off, which is indicated by a rise in the tempera- 
ture. Distillation is then discontinued, the still shut down, 
and in about an hour the contents are sufficiently cool to 
be emptied. The residue is run off into a proper receiv- 
ing vessel, treated with dilute acid and used in the distil- 
lation of tar. 

In the distillation of tar the same method as the above 
is followed, only distillation proceeds at a higher tempera- 
ture. The first portion and last portion of the distillate 
from tar are so dark that it is necessary to add them to 
a fresh charge of fatty acids. By a well conducted distil- 
lation of tar about 50 per cent, of the fatty acids from the 
tar can be used to mix with the distilled fatty acids. The 
residue of this operation called stearine pitch or candle tar 
consists of a hard, brittle, dark substance. Elastic pitch 
only results where distillation has been kept constant for 
several days without interrupting the process, and re- 
distilling the tar. In a good distillation the distillation 
loss is 0.5 to 1.5% and loss in pitch 1.5%. Fatty acids 
which are not acidified deliver about 3% of pitch. Very 
impure fats yield even a higher percentage in spite of 
acidifying. For a long time it was found impossible to 

find any use for stearine pitch, but in recent years a use 
has been found for same in the electrical installation of 
cables. 

126 



CHAPTER VI 

Analytical Methods. 

While it is possible to attain a certain amount of 
efficiency in determining the worth of the raw material 
entering into the manufacture of soap through or- 
ganoleptic methods, these are by no means accurate. 
It is, therefore, necessary to revert to chemical meth- 
ods to correctly determine the selection of fats, oil or 
other substances used in soap making, as well as stand- 
ardizing a particular soap manufactured and to properly 
regulate the glycerine recovered. 

It is not our purpose to cover in detail the numerous 
analytical processes which may be employed in the ex- 
amination of fats and oils, alkalis, soap and glycerine, 
as these are fully and accurately covered in various 
texts, but rather to give briefly the necessary tests 
which ought to be carried out in factories where large 
amounts of soap are made. Occasion often arises where 
it is impossible to employ a chemist, yet it is possible to 
have this work done by a competent person or to have 
someone instruct himself as just how to carry out 
the more simple analyses, which is not a very difficult 
matter. The various standard solutions necessary to 
carrying out the simpler titrations can readily be pur- 
chased from dealers in chemical apparatus and it does 
not take extraordinary intelligence for anyone to op- 
erate a burette, yet in many soap plants in this country 
absolutely no attention is paid to the examining of raw 
material, though many thousand pounds are handled 
annually, which, if they were more carefully examined 
would result in the saving of much more money than 

127 



i 



SOAP-MAKING MANUAL 

it costs to examine them or have them at least occa- 
sionally analyzed. 

ANALYSIS OF FATS AND OILS. 

In order to arrive at proper results in the analysis 
of a fat or oil, it is necessary to have a proper sample. 
To obtain this a sample of several of the packages of 
oil or fat is taken and these mixed or molten together 
into a composite sample which is used in making the 
tests. If the oil or fat is solid, a tester is used in taking 
the sample from the package and if they are liquid, it 
is a simple matter to draw off a uniform sample from 
each package and from these to form a composite 
sample. 

In purchasing an oil or fat for soap making, the manu- 
facturer is usually interested in the amount of free fatty 
acid contained therein, of moisture, the titer, the per- 
centage of unsaponifiable matter and to previously de- 
termine the color of soap which will be obtained where 
color is an object. 

DETERMINATION OF FREE FATTY ACIDS. 

Since the free fatty acid content of a fat or oil represents 
a loss of glycerine, the greater the percentage of free 
fatty acid, the less glycerine is contained in the fat or 
oil, it is advisable to purchase a fat or oil with the lower 
free acid, other properties and the price being the same. 

While the mean molecular weight of the mixed free 
fatty acids varies with the same and different oils or 
fats and should be determined for any particular 
analysis for accuracy, the free fatty acid is usually ex- 
pressed as oleic acid, which has a molecular weight of 
282. 

To carry out the analysis 5 to 20 grams of the fat are 

128 



ANALYTICAL METHODS 

weighed out into an Erlenmeyer flask and SO cubic cen- 
timeters of carefully neutralized alcohol are added. In 
order to neutralize the alcohol add a few drops of 
phenolphthalein solution to same and add a weak 
caustic soda solution drop by drop until a very faint 
pink color is obtained upon shaking or stirring the 
alcohol thoroughly. The mixture of fat and neutralized 
alcohol is then heated to boiling and titrated with tenth 
normal alkali sokition, using phenolphthalein as an in- 
dicator. As only the free fatty acids are readily soluble 
in the alcohol and the fat itself only slightly mixes with 
it, the flask should be well agitated toward the end of 
the titration. When a faint pink color remains after 
thoroughly agitating the flask the end point is reached. 
In order to calculate the percentage of free fatty acid 
as oleic acid, multiply the number of cubic centimeters 
of tenth normal alkali used as read on the burette by 
0.0282 and divide by the number of grams of fat taken 
for the determination and multiply by 100. 

When dark colored oils or fats are being titrated it is 
often difficult to obtain a good end point with phenolph- 
thalein. In such cases about 2 cubic centimeters of a 
2 per cent, alcoholic solution of Alkali Blue 6 B is 
recommended. 

Another method of directly determining the free fatty 
acid content of tallow or grease upon which this de- 
termination is most often made is to weigh out into an 
Erlenmeyer flask exactly 5.645 grams of a sample of 
tallow or grease. Add about 75 cubic centimeters of 
neutralized alcohol. Heat until it boils, ^hen titrate with 
tenth normal alkali and divide the reading by 2, which 
gives the percentage of free fatty acid as oleic. If a 
fifth normal caustic solution i? used, the reading on the 
burette gives the percentage of free fatty acid directly. 

129 



SOAP-MAKING MANUAL 

This method, while it eliminates the necessity of calcula- 
tion, is troublesome in that it is difficult to obtain the 
exact weight of fat. 

MOISTURE. 

To calculate the amount of moisture contained in a fat 
or oil 5 to 10 grams are weighed into a flat bottom dish, 
together with a known amount of clean, dry sand, if it 
is so desired. The dish is then heated over a water 
bath, or at a temperature of 100-110 degs. C, until it 
no longer loses weight upon drying and reweighing the 
dish. One hour should elapse between the time the 
dish is put on the water bath and the time it is taken off 
to reweigh. The difference between the weight of the 
dish is put on the water bath and the time it is taken off 
when it reaches a constant weight is moisture. This 
difference divided by the original weight of the fat or 
oil X 100 gives the percentage of moisture. 

When highly unsaturated fats or oils are being ana- 
lyzed for moisture, an error may be introduced either 
by the absorption of oxygen, which is accelerated at 
higher temperature, or by the formation of volatile fatty 
acids. The former causes an increase in weight, the 
latter causes a decrease. To obviate this, the above 
operation of drying should be carried out in the pres- 
ence of some inert gas like hydrogen, carbon dioxide, 
or nitrogen. 

TITER. 

The titer of a fat or oil is really an indication of the 
amount of stearic acid contained therein. The titer, 
expressed in degrees Centigrade, is the solidification point 
of the fatty acids of an oil or fat. In order to carry out the 
operation a Centigrade thermometer graduated in one or 
two-tenths of a degree is necessary. A thermometer grad- 

130 



ANALYTICAL METHODS 

uated between 10 degs. centigrade to 60 degs. centi- 
grade is best adapted and the graduations should be 
clear cut and distinct. 

To make the determination about 30 grams of fat are 
roughly weighed in a metal dish and 30-40 cubic centi- 
meters of a 30 per cent. (36 degs. Baume) solution of 
sodium hydroxide, together with 30-40 cubic centimeters 
of alcohol, denatured alcohol will do, are added and the 
mass heated until saponified. Heat over a low flame or 
over an asbestos plate until the soap thus formed is dry, 
constantly stirring the contents of the dish to prevent 
burning. The dried soap is then dissolved in about 1000 
cubic centimeters of water, being certain that all the 
alcohol has been expelled by boiling the soap solution 
for about half an hour. When the soap is in solution 
add sufficient sulphuric acid to decompose the soap, ap- 
proximately 100 cubic centimeters of 25 degs. Baume 
sulphuric acid, and boil until the fatty acids form a clear 
layer on top of the liquid. A few pieces of pumice stone 
put into the mixture will prevent the bumping caused by 
boiling. Siphon off the water from the bottom of the 
dish and wash the fatty acids with boiling water 
until free from sulphuric acid. Collect the fatty 
acids in a small casserole or beaker and dry them over 
a steam bath or drying oven at 110 degs. Centigrade. 
When the fatty acids are dry, cool them to about 10 
degs. above the titer expected and transfer them to a 
titer tube or short test tube which is firmly supported 
by a cork in the opening of a salt mouth bottle. Hang 
the thermometer by a cord from above the supported 
tube so it reaches close to the bottom when in the titer 
tube containing the fatty acids and so that it may be 
used as a stirrer. Stir the mass rather slowly, closely 
noting the temperature. The temperature will grad- 

131 



SOAP-MAKING MANUAL 

ually fall during the stirring operation and finally re- 
main stationary for half a minute or so then rise from 
0.1 to 0.5 degs. The highest point to which the mer- 
cury rises after having been stationary is taken as the 
reading of the titer. 

DETERMINATION OF UNSAPONIFIABLE MATTER. 

In order to determine the unsaponifiable matter in 
fats and oils they are first saponified, then the unsaponi- 
fiable, which consists mainly of hydrocarbons and the 
higher alcohols cholesterol or phytosterol, is extracted 
with ether or petroleum ether, the ether evaporated 
and the residue weighed as unsaponifiable. 

To carry out the process first saponify about 5 grams 
of fat or oil with an excess of alcoholic potassium hy- 
drate, 20-30 cubic centimeters of a 1 to 10 solution of 
potassium hydroxide in alcohol until the alcohol is 
evaporated over a steam bath. Wash the soap thus 
formed into a separatory funnel of 200 cubic centimeters 
capacity with 80-100 cubic centimeters water. Then 
add about 60 cubic centimeters of ether, .petroleum 
ether or 86 degs. gasoline and thoroughly shake the fun- 
nel to extract the unsaponifiable. Should the two layers 
not separate readily, add a few cubic centimeters of 
alcohol, which will readily cause them to separate. 
Draw off the watery solution from beneath and wash 
the ether with water containing a few drops of sodium 
hydrate and run to another dish. Pour the watery solu- 
tion into the funnel again and repeat the extraction 
once or twice more or until the ether shows no dis- 
coloration. Combine the ether extractions into the fun- 
nel and wash with water until no alkaline reaction is 
obtained from the wash water. Run the ether extract 
to a weighed dish, evaporate and dry rapidly in a drying 

132 



ANALYTICAL METHODS 

oven. As some of the hydrocarbons are readily volatile 
at 100 degs. Centigrade, the drying should not be car- 
ried on any longer than necessary. The residue is then 
weighed and the original weight of fat taken divided 
into the weight of the residue X 100 gives the percentage 
unsaponifiable. 

TEST FOR CX)LOR OF SOAP. 

It is often desirable to determine the color of the fin- 
ished soap by a rapid determination before it is made 
into soap. It often happens, especially with the tallows, 
that a dark colored sample produces a light colored 
soap, whereas a bleached light colored tallow produces 
a soap off shade. 

To rapidly determine whether the color easily washes 
out of the tallow with lye, 100 cubic centimeters of tal- 
low are saponified in an enameled or iron dish with 
100 cubic centimeters of 21 degs. Baum^ soda lye and 
100 cubic centimeters of denatured alcohol. Continue 
heating over a wire gauze until all the alcohol is ex- 
pelled and then add 50 cubic centimeters of the 21 degs. 
Baume lye to grain the soap. Allow the lyes to settle 
and with an inverted pipette draw off the lyes into a 
test tube or bottle. Close the soap with 100 cubic centi- 
meters of hot water and when closed again grain with 
50 cubic centimeters of the lye by just bringing to a 
boil over an open flame. Again allow the lyes to settle 
and put aside a sample of the lye for comparison. Re- 
peat the process of closing, graining and settling and 
take a sample of lye. If the lye is still discolored re- 
peat the above operations again or until the lye is color- 
less. Ordinarily all the color will come out with the 
third lye. The soap thus obtained contains considerable 
water which makes it appear white. The soap is, there- 
fore, dried to about 15 per cent, moisture and examined 

133 



SOAP-MAKING MANUAL 

for color. The color thus obtained is a very good cri- 
terion as to what may be expected in the soap kettle. 
By making the above analyses of fats or oils the main 
properties as to their adaptability for being made into 
soap are determined. In some cases, especially where 
adulteration or mixtures of oils are suspected, it is nec- 
essary to further analyze same. The methods of carry- 
ing out these analyses are fully covered by various texts 
on fats and oils and we will not go into details regard- 
ing the method of procedure in carrying these out. 

TESTING OF ALKALIS USED IN SOAP MAKING. 

The alkalis entering into the manufacture of soap such 
as caustic soda or sodium hydroxide, caustic potash or 
potassium hydrate, carbonate of soda or sodium carbonate, 
carbonate of potash or potassium carbonate usually con- 
tain impurities which do not enter into combination with 
the fats or fatty acids to form soap. It is out of the ques- 
tion to use chemically pure alkalis in soap making, hence 
it is often necessary to determine the alkalinity of an 
alkali. It may again be pointed out that in saponifying a 
neutral fat or oil only caustic soda or potash are efficient 
and the carbonate contained in these only combines to a 
more or less extent with any free fatty acids contained in 
the oils or fats. Caustic soda or potash or lyes made 
from these alkalis upon exposure to the air are grad- 
ually converted into sodium or potassium carbonate by 
the action of the carbon dioxide contained in the air. 
While the amount of carbonate thus formed is not very 
great and is greatest upon the surface, all lyes as well as 
caustic alkalis contain some carbonate. This carbonate 
introduces an error in the analysis of caustic alkalis when 
accuracy is required and thus in the analysis of caustic 
soda or potash it is necessary to remove the carbonate 

134 



ANALYTICAL METHODS 

when the true alkalinity as sodium hydroxide or potas- 
sium hydroxide is desired. This may be done by titration 
in alcohol which has been neutralized. 

In order to determine the alkalinity of any of the above 
mentioned alkalis, it is first necessary to obtain a repre- 
sentative sample of the substance to be analyzed. To do 
this take small samples from various portions of the pack- 
age and combine them into a composite sample. Caustic 
potash and soda are hygroscopic and samples should be 
weighed at once or kept in a well stoppered bottle. Sodium 
or potassium carbonate can be weighed more easily as 
they do not rapidly absorb moisture from the air. 

To weigh the caustic soda or potash place about five 
grams on a watch glass on a balance and weigh as rapidly 
as possible. Wash into a 500 cubic centimeter volumetric 
flask and bring to the mark with distilled water. Pipette 
off 50 cubic centimeters into a 200 cubic centimeter beaker, 
dilute slightly with distilled water, add a few drops of 
methyl orange indicator and titrate with normal acid. 
For the carbonates about 1 gram may be weighed, washed 
into a 400 cubic centimeter beaker, diluted with distilled 
water, methyl orange indicator added and titrated with 
normal acid. It is advisable to use methyl orange indi- 
cator in these titrations as phenolphthalein is affected by 
the carbon dioxide generated when an acid reacts with a 
carbonate and does not give the proper end point, unless 
the solution is boiled to expel the carbon dioxide. Litmus 
may also be used as the indicator, but here again it is 
necessary to boil as carbon dioxide also affects this sub- 
stance. As an aid to the action of these common indica- 
tors the following table may be helpful: 



135 



SOAP-MAKING MANUAL 

Color in Color in 

Indicator. Acid Alkaline Action of 

Solution. Solution. COt. 

Methyl orange Red Yellow Very slightly acid 

Phenolphthalein Colorless Red Acid 

Litmus Red Blue Acid 

It may be further stated that methyl orange at the neu- 
tral point is orange in color. 

To calculate the percentage of effective alkali from the 
above titrations, it must be first pointed out that in the 
case of caustic potash or soda aliquoit portions are 
taken. This is done to reduce the error necessarily in- 
volved by weighing, as the absorption of water is decided. 
Thus we had, say, exactly 5 grams which weighed 5.05 
grams by the time it was balanced. This was dissolved 
in 500 cubic centimeters of water and 50 cubic centimeters 
or one tenth of the amount of the solution was taken, or 
in each 50 cubic centimeters there were 0.505 grams of the 
sample. We thus reduced the error of weighing by one 
tenth provided other conditions introduce no error. In 
the case of the carbonates the weight is taken directly. 

One cubic centimeter of a normal acid solution is the 
equivalent of: Grams. 

Sodium Carbonate, NaaCOg 0.05305 

Sodium Hydroxide, NaOH 0.04006 

Sodium Oxide, NazO. 0.02905 

Carbonate KaCOs 0.06908 

Potassium Hydoxide, KOH 0.05616 

Potassium Oxide, K^O 0.04715 

Hence to arrive at the alkalinity we multiply the num- 
ber of cubic centimeters, read on the burette, by the factor 
opposite the terms in which we desire to express the al- 
kalinity, divide the weight in grams thus obtained by the 
original weight taken, and multiply the result by 100, 

136 



ANALYTICAL METHODS 

which gives the percentage of alkali in the proper terms. 
For example, say, we took the 0.505 grams, of cstustic 
potash as explained above and required 8.7 cubic centi- 
meter normal acid to neutralize the solution, then 

8.7 X .05616 = .4886 grams KOH in sample 

.4886 

X 100 = 96.73% KOH in sample. 

.505 

Caustic potash often contains some caustic soda, and 
while it is possible to express the results in terms of KOH, 
regardless of any trouble that may be caused by this mix- 
ture in soap making, an error is introduced in the results, 
not all the alkali being caustic potash. In such cases it is 
advisable to consult a book on analysis as the analysis 
is far more complicated than those given we will not 
consider it. The presence of carbonates, as already stated, 
also causes an error. To overcome this the alkali is titrated 
in absolute alcohol, filtering off the insoluble carbonate. 
The soluble portion is caustic hydrate and may be titrated 
as such. The carbonate remaining on the filter paper is 
dissolved in water and titrated as carbonate. 

SOAP ANALYSIS. 

To obtain a sample of a cake of soap for analysis is a 
rather difficult matter as the moisture content of the outer 
and inner layer varies considerably. To overcome this 
difficulty a borer or sampler may be run right through 
the cake of soap, or slices may be cut from various parts 
of the cake, or the cake may be cut and run through a 
meat chopper several times and mixed. A sufficient 
amount of a homogeneous sample obtained by any of these 
methods is preserved for the entire analysis by keeping the 
soap in a securely stoppered bottle. 

The more important determinations of soap are moist- 
ure, free alkali, or fatty acid, combined alkali and total 

137 



fT 



SOAP-MAKING MANUAL 

fatty matter. Besides these it is often necessary to de- 
termine insoluble matter, glycerine, unsaponifiable matter, 
rosin and sugar. 

MOISTURE. 

The analysis of soap for moisture, at its best, is most 
unsatisfactory, for by heating it is impossible to drive off 
all the water, and on the other hand volatile oils driven 
off by heat are a part of the loss represented as moisture. 

The usual method of determining moisture is to weigh 
2 to 3 grams of finely shaved soap on a watch glass and 
heat in an oven at 105 degrees C. for 2 to 3 hours. The 
loss in weight is represented as water, although it is really 
impossible to drive off all the water in this way. 

To overcome the difficulties just mentioned either the 
Smith or Fahrion method may be used. Allen recom- 
mends Smith's method which is said to be truthful to 
within 0.25 per cent. Fahrion*s method, according to 
the author, gives reliable results to within 0.5 per cent. 
Both are more rapid than the above manipulation. To 
carry out the method of Smith, 5 to 10 grams of finely 
ground soap are heated over a sand bath with a small 
Bunsen flame beneath it, in a large porcelain crucible. 
The heating takes 20 to 30 minutes, or until x\6 further 
evidence is present of water being driven off. This may 
be tested by the fogging of a cold piece of glass held over 
the crucible immediatel|r upon removing the burner. When 
no fog appears the soap is considered dry. Any lumps of 
soap may be broken up by a small glass rod, weighed with 
the crucible, and with a roughened end to more easily 
separate the lumps. Should the soap burn, this can readily 
be detected by the odor, which, of course, renders the 
analysis useless. The loss in weight is moisture. 

138 



ANALYTICAL METHODS 

By Fahrion*s method*, 2 to 4 grams of soap are weighed 
in a platinum crucible and about three times its weight 
of oleic acid, which has been heated at 120 degrees C. until 
all the water is driven off and preserved from moisture, * 
is added and reweighed. The dish is then cautiously 
heated with a small flame until all the water is driven off 
and all the soap is dissolved. Care must be exercised not 
to heat too highly or the oleic acid will decompose. The mo- 
ment the water is all driven off a clear solution is formed, 
provided no fillers are present in the soap. The dish is 
then cooled in a dessicator and reweighed. The loss in 
weight of acid plus soap is moisture and is calculated on 
the weight of soap taken. This determination takes about 
fifteen minutes. 

FREE ALKALI OR ACID. 

(a) Alcoholic Method. 

Test a freshly cut surface of the soap with a few drops 
of an alcoholic phenolphthalein solution. If it does not 
turn red it may be assumed free fat is present; should a 
red color appear, free alkali is present. In any case dis- 
solve 2 to 5 grams of soap in 100 cubic centimeters of 
neutralized alcohol and heat to boiling until in solution. 
Filter off the undissolved portion containing carbonate, 
etc., and wash with alcohol. Add phenolphthalein to the 
filtrate and titrate with N/10 acid and calculate the per 
cent, of free alkali as sodium or potassium hydroxide. 
Should the filtrate be acid instead of -alkaline, titrate with 
N/10 alkali and calculate the percentage of free fatty acid 
as oleic acid. 

The insoluble portion remaining on the filter paper is 
washed with water until all the carbonate is dissolved. 
The washings are then titrated with N/10 sulfuric acid 

•Zcit. Angcw. Chcm. 19, 385 (1906). 

139 



SOAP-MAKING MANUAL 

and expressed as sodium or potassium carbonate. Should 
borates or silicates be present it is possible to express in 
terms of these. If borax is present the carbon dioxide is 
boiled off after neutralizing exactly to methyl orange ; cool, 
add mannite and phenolphthalein and titrate the boric acid 
with standard alkali. 

(b) Bosshard and Huggenberg Method.^ 

In using the alcoholic method for the determination of 
the free alkali or fat in soap there is a possibility of both 
free fat and free alkali being present. Upon boiling in an 
alcoholic solution the fat will be saponified, thus intro- 
ducing an error in the analysis. The method of Bosshard 
and Huggenberg overcomes this objection. Their method 
is briefly as follows: 

Reagents, 

1. N/10 hydrochloric acid to standardize N/10 alcoholic 
sodium hydroxide. 

2. Approximately N/10 alcoholic sodium hydroxide to 
fix and control the N/40 stearic acid. 

3. N/40 stearic acid. Preparation: About 7.1 grams of 
stearic acid are dissolved in one liter of absolute alcohol, 
the solution filtered, the strength determined by titration 
against N/10 NaOH and then protected in a well stop- 
pered bottle, or better still connected directly to the 
burette. 

4. A 10 per cent, solution of barium chloride. Prepara- 
tion : 100 grams of barium chloride are dissolved in one 
liter of distilled water and filtered. The neutrality of the 
solution should be proven as it must be neutral. 

5. a naphtholphthalein indicator . according to Soren- 
son. Preparation: 0.1 gram of a naphtholphthalein is 
dissolved in 150 cubic centimeters of alcohol and 100 cubic 



tZeit. Angcw. Chcm. 27. 11-20 (1914). 

140 



ANALYTICAL METHODS 

centimeters of water. For every 10 cubic centimeters of 
liquid use at least 12 drops of indicator. 

6. Phenolphthalein solution 1 gram to 100 cubic centi- 
meter 96 per cent, alcohol. 

7. Solvent, 50 per cent, alcohol neutralized. 

MANIPULATION. 

First — Determine the strength of the N/10 alcoholic so- 
dium hydroxide in terms of N/10 hydrochloric acid and 
calculate the factor, e. g. : 

10 C.C. N/10 alcoholic NaOH = 9.95 N/10 HCI ) ^^ 

10 c.c. N/10 alcoholic NaOH = 9.96 N/10 HCI \ ^ 
The alcoholic N/10 NaOH has a factor of 0.996. 

Second — Control the N/40 stearic acid with the above 
alkali to obtain its factor, e. g. : 

40 c.c. N/40 alcoholic stearic acid = 

10.18 C.C. N/10 NaOHl 

40 c.c. N/40 alcoholic stearic acid = )■ 10.2 

10.22 c.c. N/10 NaOH J 
10.2 X F N/10 NaOH (0.996) = Factor N/40 stearic acid 
.'.Factor N/40 stearic acid = 1.016. 

Third — About 5 grams of soap are weighed and dis- 
solved in 100 cubic centimeters of 50 per cent, neutralized 
alcohol in a 250 cubic centimeter Erlenmeyer flask over a 
water bath and connected with a reflux condensor. When 
completely dissolved, which takes but a few moments, it 
is cooled by allowing a stream of running water to run 
over the outside of the flask. 

Fourth — The soap is precipitated with 15 to 20 cubic 
centimeters of the 10 per cent, barium chloride solution. 

Fifth — After the addition of 2 to 5 cubic centimeters of 
a naphtholphthalein solution the solution is titrated with 
N/40 alcoholic stearic acid, a naphtholphthalein is red 
with an excess of stearic acid. To mark the color changes 

141 



SOAP-MAKING MANUAL 

It is advisable to first run a few blanks until the eye has 
become accustomed to the change in the indicator in the 
same way. The change from green to red can then be 
carefully observed. 

Let us presume 5 grams of soap were taken for the 
analysis and 20 cubic centimeters of N/40 stearic acid 
were required for the titration then to calculate the 
amount of NaOH since the stearic factor is 1.016. 

20 X 1.016 = 20.32 N/40 stearic acid really required. 

1 cubic centimeter N/40 stearic acid = 0.02 per cent. 
NaOH for 5 grams soap. 

A 20.32 cubic centimeters N/40 stearic acid = 0.02 X 
20.32 per cent. NaOH for 5 grams soap. 

Hence the soap contains 0.4064 per cent. NaOH. 

It is necessary, however, to make a correction by this 
method. When the free alkali amounts to over 0.1 per 
cent, the correction is + 0.01, and when the free alkali 
exceeds 0.4 per cent, the correction is + 0.04, hence in the 
above case we multiply 0.004064 by 0.04, add this amount 
to 0.004064 and multiply by 100 to obtain the true per- 
centage. Should the alkalinity have been near 0.1 per cent, 
we would have multiplied by 0.01 and added this. 

If carbonate is also present in the soap, another 5 grams 
of soap is dissolved in 100 cubic centimeters of 50 per 
cent, alcohol and the solution titrated directly after cooling 
with N/40 stearic acid, using a naphtholphthalein or 
phenolphthalein as an indicator, without the addition of 
barium chloride. From the difference of the two titra- 
tions the alkali present as carbonate is determined. 

If the decomposed soap solution is colorless with 
phenolphthalein, free fatty acids are present, which may 
be quickly determined with alcoholic N/10 sodium hy- 
droxide. 

142 



1 



ANALYTICAL METHODS < / ^ 

INSOLUBLE MATTER. <■ 

The insoluble matter in soap may consist of organic or 
inorganic substances. Among the organic substances wjiich 
are usually present in soap are oat meal, bran, sawdust, .etc., 
while among the common inorganic or mineral compounds 
are pumice, silex, clay, talc, zinc oxide, infusorial earth, 
sand or other material used as fillers. 

To determine insoluble matter, 5 grams of soap are 4itS- 
solved in 75 cubic centimeters of hot water. The solution 
is filtered through a weighed gooch crucible or filter paper. 
The residue remaining on the filter is washed with hot 
water until all the soap is removed, is then dried to.otMistant 
weight at 105 degrees C. and weighed. From the difference 
in weight of the gooch or filter paper and the dried residue 
remaining thereon after filtering and drying, the total per- 
centage of insoluble matter may easily be calculated. By 
igniting the residue and reweighing the amount of in- 
soluble mineral matter can be readily determined. 

STARCH AND GELATINE. 

Should starch or gelatine be present in Soap it is neces- 
sary to extract 5 grams of the soap with 100 cubic centi- 
meters of 95 per cent, neutralised alcohol in a Soxhlet ex- 
tractor until the residue on the extraction thimble is in a 
powder form. If necessary the apparatus should be discon- 
nected and any lumps crushed, as these may contain soap. 
The residue remaining on the thimble consists of all sub- 
stances present in soap, insoluble in alcohol. This is dried 
and weighed so that any percentage of impurities not 
actually determined can be found by difference. Starch and 
gelatine are separated from carbonate, sulfate and borate by 
dissolving the latter out through a filter with cold water. The 
starch and gelatine thus remaining can be determined by 

143 



t 



SOAP-MAKING MANUAL 

known methods, starch by the method of direct hydrolysis* 
and gelatine by Kjeldahling and calculating the correspond- 
ing amount of gelatine from the percentage of nitrogen 
(17.9%) therein.' 

TOTAL FATTY AND RESIN ACIDS. 

To the filtrate from the insoluble? matter add 40 cubic 
centimeters of half normal sulfuric acid, all the acid being 
added at once. Boil, stir thoroughly for some minutes and 
keep warm on a water bath until the fatty acids have col- 
lected as a clear layer on the surface. Cool by placing the 
beaker in ice and syphon off the acid water through a filter. 
Should the fatty acids not readily congeal a weighed amount 
of dried bleached bees-wax or stearic acid may be added to 
the hot mixture. This fuses with the hot mass and forms a 
firm cake of fatty acids upon cooling. Without removing the 
fatty acids from the beaker, add about 300 cubic centimeters 
of hot water, cool, syphon off the water through the same 
filter used before and wash again. Repeat washing, cooling 
and syphoning processes until the wash water is no longer 
acid. When this stage is reached, dissolve any fatty acid 
which may have remained on the filter with hot 95 per cent, 
alcohol into the beaker containing the fatty acids. Evap- 
orate the alcohol and dry the beaker to constant weight 
over a water bath. The fatty acids thus obtained repre- 
sent the combined fatty acids, uncombined fat and 
hydrocarbons. 

DETERMINATION OF ROSIN. 

If cesin acids are present, this may be determined by 
the Li«fiermann-Storch reaction. To carry out this test 
shake 2 cubic centimeters of the fatty acids with 5 cubic 



iBuU. 107, Bur. Chem. U. S. Dept. Agriculture. 
•Richards and Gies Am. J. Physiol. (1902) 7, 129. 

^44 



-^-4 



1 



ANALYTICAL METHODS 

centimeters of acetic anhydride; warm slightly; cool; draw^ 
off the anhydride and add 1 :1 sulfuric acid. A violet 
color, which is not permanent, indicates the presence of 
rosin in the soap. The cholesterol in linseed or fish oil, 
which of course may be present in the soap, also give this 
reaction. 

Should resin acids be present, these may be separated 
by the Twitchell method, which depends upon the difference 
in the behavior of the fatty and resin acids when con- 
verted into their ethyl esters through the action of hydro- 
chloric acid. This may be carried out as follows: 

Three grams of the dried mixed acids are dissolved in 
25 cubic centimeters of absolute alcohol in a 100 cubic 
centimeter stoppered flask; the flask placed in cold water 
and shaken. To this cooled solution 25 cubic centimeters of 
absolute alcohol saturated with dry hydrochloric acid is 
added. The flask is shaken occasionally and the action 
allowed to continue for twenty minutes, then 10 grams of 
dry granular zinc chloride are added, the flask shaken and 
again allowed to stand for twenty minutes. The contents 
of the flask are then poured into 200 cubic centimeters of 
water in a 500 cubic centimeter beaker and the flask rinsed 
out with alcohol. A small strip of zinc is placed in 
the beaker and the alcohol evaporated. The beaker is 
then cooled and transferred to a separatory funnel, wash- 
ing out the beaker with 50 cubic centimeters of gasoline 
(boiHng below 80 degrees C.) and extracting by shaking 
the funnel well. Draw off the acid solution after allowing 
to separate and wash the gasoline with water until -free 
from hydrochloric acid. Draw off the gasoline solution 
and evaporate the gasoline. Dissolve the residue in 
neutral alcohol and titrate with standard alkali using 
phenolphthalein as an indicator. One cubic centimeter of 
normal alkali equals 0.346 grams of rosin. The rosin may 

145 



/ 



SOAP-MAKING MANUAL 

be gravimetrically determined by washing the gasoline ex- 
tract with water, it not being necessary to wash absolutely 
free from acid, then adding 0.5 gram of potassium 
hydroxide and 5 cubic centimeters of alcohol in 50 cubic 
centimeters of water. Upon shaking the resin acids are 
rapidly saponified and extracted by the dilute alkaline solu- 
tion as rosin soaps, while the ethyl esters remain in solution 
in the gasoline. Draw off the soap solution, wash the 
gasoline solution again with dilute alkali and unite the 
alkaline solutions. Decompose the alkaline soap solution with 
an excess of hydrochloric acid and weigh the resin acidi 
liberated as in the determination of total fatty acids. 

According to Lewkowitsch, the results obtained by the 
volumetric method which assumes a combining weight of 
346 for resin acids, are very likely to be high. On the 
other hand those obtained by the gravimetric method are 
too low. 

Leiste and StiepeP have devised a simpler method for 
the determination of rosin. They make use of the fact 
that the resin acids as sodium soaps are soluble in acetone 
and particularly acetone containing two per cent, water, 
while the fatty acid soaps are soluble in this solvent to 
the extent of only about 2 per cent. First of all it is 
necessary to show that the sample to be analyzed contains 
a mixture of resin and fatty acids. This may be done 
by the Liebermann-Storch reaction already described. 
Glycerine interferes with the method. Two grams of fatty 
acids or 3 grams of soap are weighed in a nickel crucible 
and dissolved in 15-20 cubic centimeters of alcohol. The 
solution is then neutralized with alcoholic sodium hydroxide, 
using phenolphthalein as an indicator. The mass is con- 
centrated by heat over an asbestos plate until a slight film 



1 Seifensieder Ztg. 0913) No. 46. 

146 



ANALYTICAL METHODS 

torms over it. Then about 10 grams of sharp, granular, 
ignited sand are stirred in by means of a spatula, the 
alcohol further evaporated, the mixture being constantly 
stirred and then thoroughly dried in a drying oven. The 
solvent for the cooled mass is acetone containing 2 per 
cent, water. It is obtained from acetone dried by ignited 
sodium sulfate and adding 2 per cent, water by volume. 
One hundred cubic centimeters of this solvent are sufficient 
for extracting the above. The extraction of the rosin soap 
is conducted by adding 10 cubic centimeters of acetone 
eight times, rubbing the mass thoroughly with a spatula 
and decanting. The decanted portions are combined in a 
beaker and the suspended fatty soaps allowed to separate. 
The mixture is then filtered into, a previously weighed 
flask and washed several times with the acetone remaining. 
The solution of rosin soap should show no separation of 
solid matter after having evaporated to half the volume 
and allowing to cool. If a separation should occur another 
filtration and the slightest possible washing is necessary. 
To complete the analysis, the acetone is completely evap- 
orated and the mass dried to constant weight in a drying 
oven. The weight found gives the weight of the rosin 
soap. In conducting the determination, it is important to 
dry the mixture of soap and sand thoroughly. In dealing 
with potash soaps it is necessary to separate the fatty 
acids from these and use them as acetone dissolves too 
great a quantity of a potash soap. 

TOTAL ALKALI. 

In the filtrate remaining after having washed the fatty 
acids in the determination of total fatty and resin acids 
all the alkali present as soap, as carbonate and as hydroxide 
remains in solution as sulfate. Upon titrating this solu- 
tion with half normal alkali the difference between the 

147 



SOAP-MAKING MANUAL 

half normal acid u«ed in decomposing the soap and alkali 
used in titrating the excess of acid gives the amount of 
total alkali in the soap. By deducting the amount of free 
alkali present as carbonate or hydroxide previously found 
the amount of combined alkali in the soap may be 
calculated. 

i To quickly determine total alkali in soap a weighed 
/ portion of the soap may be ignited to a white ash and the 
\4ish titrated for alkalinity using methyl orange as an in- 
dicator. 

UNSAPONIFIED MATTER. 

Dissolve 5 grams of soap in 50 cubic centimeters of 50 
per cent, alcohol. Should any free fatty acids be present 
neutralize them with standard alkali. Wash into a separa- 
tory funnel with 50 per cent, alcohol and extract with 
100 cubic centimeters of gasoline, boiling at 50 degrees to 
60 degrees C. Wash the gasoline with water, draw off the 
watery layer. Run the gasoline into a weighed dish, evap- 
orate the alcohol, dry and weigh the residue as unsaponi- 
fied matter. The residue contains any hydrocarbon oils 
or fats not converted into soap. 

SILICA AND SILICATES. 

The insoluble silicates, sand, etc., are present in the 
ignited residue in the determination of insoluble matter. 
Sodium silicate, extensively used as a filler, however, will 
only show itself in forming a pasty liquid. Where it is 
desired to determine sodium silicate, 10 grams of soap are 
ashed by ignition, hydrochloric acid added to the ash in 
excess and evaporated to dryness. More hydrochloric acid 
is then added and the mass is again evaporated until dry; 
then cooled; moistened with hydrochloric acid; dissolved 
in water; filtered; washed; the filtrate evaporated to dry- 
ness and again taken up with hydrochloric acid and water; 

148 



^ 



ANALYTICAL METHODS 

filtered and washed. The precipitates are then combined 
and ignited. Silicon dioxide (SiO,) is thus formed, which 
can be calculated to sodium silicate (NaaSi40»). Should 
other metals than alkali metals be suspected present the 
filtrate from the silica determinations should be examined. 

GLYCERINE IN SOAP. /, 

To determine the amount of glycerine contained in soag^ 
dissolve 25 grams in hot water, add a slight excess* of \ 
sulfuric acid and keep hot until the fatty acids form as ay 
clear layer on top. Cool the mass and remove the fatty 
acids. Filter the acid solution into a 25 cubic centimeter 
graduated flask; bring to the mark with water and de- 
termine the glycerine by the bichromate method as de- 
scribed under glycerine analysis. 

When sugar is present the bichromate would be reduced 
by the sugar, hence this method is not applicable. In this 
case remove the fatty acids as before, neutralize an aliquot 
portion with milk of lime, evaporate to 10 cubic centi- 
meters, add 2 grams of sand and milk of lime containing 
about 2 grams of calcium hydroxide and evaporate almost 
to dryness. Treat the moist residue with 5 cubic centi- 
meters of 96 per cent, alcohol, rub the whole mass into a 
paste, then constantly stirring, heat on a water bath and 
decant into a 250 cubic centimeter graduated flask. Re- 
peat the washing with 5 cubic centimeters of alcohol five 
or six times, each time pouring the washings into the 
flask; cool the flask to room temperature and fill to the 
mark with 96 per cent, alcohol, agitate the flask until well 
mixed and filter through a dry filter paper. Take 200 cubic 
centimeters of the filtrate and evaporate to a syrupy con- 
sistency over a safety water bath. Wash the liquor into 
a stoppered flask with 20 cubic centimeters of absolute 
alcohol, add 30 cubic centimeters of absolute ether 10 

149 



1 ^ 



SOAP-MAKING MANUAL 

cubic centimeters at a time, shaking well after each addi- 
tion and let stand until clear. Pour off the solution 
through a filter into a weighed dish and wash out the 
flask with a mixture of three parts absolute ether and two 
parts absolute alcohol. Evaporate to a syrup, dry for one 
hour at the temperature of boiling water, weigh, ignite 
and weigh again. The loss is glycerine. This multiplied 
hy 5/4 gives the total loss for the aliquot portion taken. 
The glycerine may also be determined by the acetin or 
bichromate methods after driving off the alcohol and ether 
if so desired. 

SUGAR IN SOAP. 

To determine sugar in soap, usually present in trans- 
parent soaps, decompose a soap solution of 5 grams of 
soap dissolved in 100 cubic centimeters of hot water with 
an excess of hydrochloric acid and separate the fatty acids 
as usual. Filter the acid solution into a graduated flask 
and make up to the mark. Take an aliquot containing 
approximately 1 per cent, of reducing sugar and determine 
the amount of sugar by the Soxhlet method.^ 

GLYCERINE ANALYSIS. 

The methods of analyzing glycerine varied so greatly 
due to the fact that glycerine contained impurities which 
acted so much like glycerine as to introduce serious errors 
in the determinations of crude glycerine. This led to the 
appointment of committees in the United States and 
Europe to investigate the methods of glycerine analysis. 
An international committee met after their investigations 
and decided the acetin method should control the buying 
and selling of glycerine, but the more convenient 
bichromate method in a standardized form might be used 



»Bull 107, Bur. Chem. U. S. Dept. Agriculture. 

150 



ANALYTICAL METHODS 

in factory control and other technical purposes. The 
following are the methods of analysis and sampling as 
suggested by the international committee: 

SAMPLING. 

The most satisfactory method available for sampling 
crude glycerine liable to contain suspended matter, or 
which is liable to deposit salt on settling, is to have the 
glycerine sampled by a mutually approved sampler as soon 
as possible after it is filled into drums, but in any case be- 
fore any separation of salt has taken place. In such cases 
he shall sample with a sectional sampler (see appendix) 
then seal the drums, brand them with a number for 
identification, and keep a record of the brand number. 
The presence of any visible salt or other suspended mat- 
ter is to be noted by the sampler, and a report of the same 
made in his certificate, together with the temperature of 
the glycerine. Each drum must be sampled. Glycerine 
which has deposited salt or other solid matter cannot be 
accurately sampled from the drums, but an approximate 
sample can be obtained by means of the sectional sampler, 
which will allow a complete vertical section of the glycerine 
to be taken including any deposit. 

ANALYSIS. 

1. Determination of Free Caustic Alkali. — Put 20 grams 
of the sample into a 100 cc. flask, dilute with approx- 
imately 50 cc. of freshly boiled distilled water, add an 
excess of neutral barium chloride solution, 1 cc. of 
phenolphthalein solution, make up to the mark and mix. 
Allow the precipitate to settle, draw off 50 cc. of the clear 
liquid and titrate with normal acid (N/l). Calculate the 
percentage of Na^O existing as caustic alkali. 

2. Determination of Ash and Total Alkalinity. — Weigh 

151 



SOAP-MAKING MANUAL 

2 to 5 grams of the sample in a platinum dish, bum off the 
glycerine over a luminous Argand burner or other source 
of heat/ giving a low temperature, to avoid volatilization 
and the formation of sulphides. When the mass is charred 
to the point that water will not be colored by soluble or- 
ganic matter, lixiviate with hot distilled water, filter, wash 
and ignite the residue in the platinum dish. Return the 
filtrate and washings to the dish, evaporate the water, and 
carefully ignite without fusion. Weigh the ash. 

Dissolve the ash in distilled water and titrate total al- 
kalinity, using as indicator methyl orange cold or litmus 
boiling. 

3. Determination of Alkali Present as Carbonate. — Take 
10 grams of the sample, dilute with 50 cc. distilled water, 
add sufficient N/1 acid to neutralize the total alkali found 
at (2), boil under a reflux condenser for 15 to 20 minutes, 
wash down the condenser tube with distilled water, free 
from carbon dioxide, and then titrate back with N/l 
NaOH, using phenolphthalein as indicator. Calculate the 
percentage of NaaO. Deduct the Na^O found in (1). The 
difference is the percentage of NaaO existing as carbonate. 

4. Alkali Combined with Organic Acids, — The sum of 
the percentages of NaaO found at (1) and (3) deducted 
from the percentage found at (2) is a measure of the 
NajO or other alkali combined with organic acids. 

5. Determination of Acidity. — Take 10 grams of the 
sample, dilute with 50 cc. distilled water free from carbon 
dioxide, and titrate with N/l NaOH and phenolphthalein. 
Express in terms of NaaO required to neutralize 100 grams. 

6. Determination of Total Residue at 160° C. — For this 
determination the crude glycerine should be slightly alka- 
line with NajCOs not exceeding 0.2 per cent. NajO, in 

* Carbon is readily burned off completely, without loss of chlor- 
ides, in a gas-heated muffle furnace adjusted to a dull red haat. 

152 



ANALYTICAL METHODS 

order to prevent loss of organic acids. To avoid the for- 
mation of polyglycerols this alkalinity must not be ex- 
ceeded. 

Ten grams of the sample are put into a 100 cc flask, 
diluted with water and the calculated quantity of N/\ 
HCl or NaaCOs added to give the required degree of 
alkalinity. The flask is filled to 100 cc, the contents 
mixed, and 10 cc. measured into a weighed Petrie or 
similar dish 2.5 in. in diameter and 0.5 in. deep, which 
should have a flat bottom. In the case of crude glycerine 
abnormally high in organic residue a smaller amount 
should be taken, so that the weight of the organic residue 
does not materially exceed 30 to 40 milligrams. 

The dish is placed on a water bath (the top of the 160° 
oven acts equally well) until most of the water has evap- 
orated. From this point the evaporation is effected in 
the oven. Satisfactory results are obtained in an oven' 
measuring 12 ins. cube, having an iron plate 0.75 in. thick 
Ijdng on the bottom to distribute the heat. Strips of ab- 
bestos millboard are placed on a shelf half way up the 
oven. On these strips the dish containing the glycerine 
is placed. 

If the temperature of the oven has been adjusted to 
160* C. with the door closed, a temperature of 130° to 
140* can be readily maintained with the door partially 
open, and the glycerine, or most of it, should be evap- 
orated off at this temperature. When only a slight 
vapor is seen to come off, the dish is removed and allowed 
to cool. 

An addition of 0.5 to 1.0 cc. of water is made, and by 



^ An electric oven suitable for this work, which is readily ad- 
justed to 160 degs. C, has been made for Mr. Low and the chair- 
man, by the Apparatus and Specialty Company, Lansing, Mich. 
Its size is 9^ x 10 x 16 inches, and capacity 8 Petrie dishes. It 
ffiTes a strong draft at constant temperature. 

153 



r 



30AP-MAKING MANUAL 

a rotary motion the residue brought wholly or nearly 
into solution. The dish is then allowed to remain on a 
water bath or top of the oven until the excess water has 
evaporated and the residue is in such a condition that 
on returning to the oven at 160** C. it will not spurt. The 
time taken up to this point cannot be given definitely, nor 
is it important. Usually two or three hours are required. 
From this point, however, the schedule of time must be 
strictly adhered to. Tiie dish is allowed to remain in 
the oven, the temperature of which is carefully main- 
tained at 160° C. for one hour, when it is removed, 
cooled, the residue treated with water, and the water 
evaporated as before. The residue is then subjected to 
a second baking of one hour, after which the dish is 
allowed to cool in a desiccator over sulphuric acid and 
weighed. The treatment with water, etc., is repeated 
until a constant loss of 1 to 1.5 mg. per hour is obtained. 

In the case of acid glycerine a correction must be 
made for the alkali added 1 cc. iV/1 alkali represents an 
addition of 0.03 gram. In the case of alkaline crudes a 
correction should be made for the acid added. Deduct 
the increase in weight due to the conversion of the 
NaOH and NasCOs to NaCl. The corrected weight 
multiplied by 100 gives the percentage of total residue 
at 160** C. 

This residue is taken for the determination of the 
non- volatile acetylizable impurities (see acetin method). 

7. Organic residue. — Subtract the ash from the total 
residue at 160** C. Report as organic residue at 160° C. 
(it should be noted that alkaline salts of fatty acids are 
converted to carbonates on ignition and that the CO. 
thus derived is not included in the organic residue). 

154 



ANALYTICAL METHODS 



rly 
a 

las 
tat 
he 
or 
d. 



ACETIN PROCESS FOR THE DETERMINATION OF GLYCEROL. 

This process is the one agreed upon at a conference of 
delegates from the British, French, German and American 
committees, and has been confirmed by each of the above 
committees as giving results nearer to the truth than the 
bichromate method on crudes in general. It is the process 
to be used (if applicable) whenever only one method is 
^ employed. On pure glycerines the results are identical 

m with those obtained by the bichromate process. For the 

1- application of this method the crude glycerine should not 

1, contain over 60 per cent, water. 

'^ REAGENTS REQUIRED. 

^ (A) Best Acetic Anhydride. — This should be carefully 

s selected. A good sample must not require more than 0.1 

' cc. normal NaOH for saponification of the impurities when 

I a blank is run on 7.5 cc. Only a slight color should de- 

velop during digestion of the blank. 
. I The anhydride may be tested for strength by the fol- 

1 ! lowing method: Into a weighed stoppered vessel, con- 

taining 10 to 20 cc. of water, run about 2 cc. of the anhy- 
i dride, replace the stopper and weigh. Let stand with oc- 
\ cassional shaking, for several hours, to permit the hydro- 
' lysis of all the anhydride ; then dilute to about 200 cc, add 

phenolphthalein and titrate with N/l NaOH. This gives 
the total acidity due to free acetic acid and acid formed 
from the anhydride. It is worthy of note that in the 
presence of much free anhydride a compound is formed 
\ with phenolphthalein, soluble in alkali and acetic acid, but 
insoluble in neutral solutions. If a turbidity is noticed 
toward the end of the neutralization it is an indication that 
the anhydride is incompletely hydrolyzed and inasmuch as 
the indicator is withdrawn from the solution, results may 
be incorrect 

155 



; 



SOAP-MAKING MANUAL 

Into a stoppered weighing bottle containing a known 
weight of recently distilled aniline (from 10 to 20 cc.) 
measure about 2 cc. of the sample, stopper, mix, cool and 
weigh. Wash the contents into about 200 cc. of cold water, 
and titrate the acidity as before. This yields the acidity 
due to the original, preformed, acetic acid plus one-half 
the acid due to anhydride (the other half having formed 
acetanilide) ; subtract the second result from the first 
(both calculated to 100 grams) and double the result, ob- 
taining the cc. N/\ NaOH per 100 grams of the sample. 
1 cc. i\^/NaOH equals 0.0510 anhydride. 

(5) Pure Fused Sodium Acetate. — The purchased salt 
is again completely fused in a platinum, silica or nickel 
dish, avoiding charring, powdered quickly and kept in a 
stoppered bottle or desiccator. It is most important that 
the sodium acetate be anhydrous. 

(C) A Solution of Caustic Soda for Neutralizing, of 
about N/1 Strength, Free from Carbonate. — ^This can be 
readily made by dissolving pure sodium hydroxide in its 
own weight of water (preferably water free from carbon 
dioxide) and allowing to settle until clear, or filtering 
through an asbestos or paper filter. The clear solution is 
diluted with water free from carbon dioxide to the strength 
required. , 

(D) N/\ Caustic Soda Free from Carbonate. — Pre- 
pared as above and carefully standardized. Some caustic 
soda solutions show a marked diminution in strength after 
being boiled; such solutions should be rejected. 

(£) N/\ Acid. — Carefully standardized. 
(F) Phenolphthalein Solution. — 0.5 per cent, phenol- 
phthalein in alcohol and neutralized. 

THE METHOD. 

In a narrow-mouthed flask (preferably round-bot- 

156 



ANALYTICAL ^METHODS 

tomed), capacity about 120 cc, which has been thoroughly 
cleaned and dried, weigh accurately and as rapidly as pos- 
sible L25 to L5 grams of the glycerine. A Grethan or 
Lunge pipette will be found convenient. Add about 3 
grams of the. anhydrous sodium acetate, then 7.5 cc. ef the 
acetic anhydride, and connect the flask with an upright 
Liebig condenser. For convenience the inner tube of this 
condenser should not be over 50 cm. long and 9 to 10 mm. 
inside diameter. The flask is connected to the condenser 
by either a ground glass joint (preferably) or a rubber 
stopper. If a rubber stopper is used it should have had a 
preliminary treatment with hot acetic anhydride vapor. 

Heat the contents and keep just boiling for one hour, 
taking precautions to prevent the salts drying on the sides 
of the flask. 

Allow the flask to cool somewhat, and through the con- 
denser tube add 50 cc. of distilled water free from carbon 
dioxide at a temperature of about 80** C, taking care that 
the flask is not loosened from the condenser. The object 
of cooling is to avoid any sudden rush of vapors from the 
flask on adding water, and to avoid breaking the flask. 
Time is saved by adding the water before the contents of 
the flask solidify, but the contents may be allowed to solid- 
ify and the test proceeded with the next day without detri- 
ment, bearing in mind that the anhydride in excess is much 
more effectively hydrolyzed in hot than in cold water. The 
contents of the flask may be warmed to, but must not ex- 
ceed, 80° C, until the solution is complete, except a few 
dark flocks representing organic impurities in the crude. 
By giving the flask a rotary motion, solution is more 
quickly effected. 

Cool the flask and contents without loosening from the 
condenser. When quite cold wash down the inside of the 
condenser tube, detach the flask, wash off the stopper or 

157 



SOAP-MAKING MANUAL 

ground glass connection into the flask, and filter the contents 
through an acid-washed filter into a Jena glass flask of 
about 1 litre capacity. Wash thoroughly with cold distilled 
water free from carbon dioxide. Add 2 cc. of phenol- 
phthalein solution (F), then run in caustic soda solution 
(C) or (D) until a faint pinkish yellow color appears 
throughout the solution. This neutralization must be done 
most carefully ; the alkali should be run down the sides of 
the flask, the contents of which are kept rapidly swirling 
with occasional agitation or change of motion until the 
solution is nearly neutralized, as indicated by the slower 
disappearance of the color developed locally by the alkali 
running into the mixture. When this point is reached 
the sides of the flask are washed down with carbon 
dioxide-free water and the alkali subsequently added drop 
by drop, mixing after each drop until the desired tint 
is obtained. 

Now run in from a burette 50 cc. or a calculated excess 
of N/1 NaOH (D) and note carefully the exact amount. 
Boil gently for 15 minutes, the flask being fitted with a 
glass tube acting as a partial condenser. Cool as quickly 
as possible and titrate the excess of NaOH with A^/1 acid 
(E) until the pinkish yellow or chosen end-point color 
just remains.* A further addition of the indicator at this 
point will cause an increase of the pink color; this must 
be neglected, and the first end-point taken. 

From the N/l NaOH consumed calculate the percentage 
of glycerol (including acetylizable impurities) after mak- 
ing the correction for the blank test described below. 

1 cc. N/l NaOH = 0.03069 gram glycerol. 

The coefficient of expansion for normal solutions is 



^A precipitate at this point is an indication of the presence of 
iron or alumina, and high results will be obtained unless a cor- 
rection is made as described below. 

158 



^.BBalH 



ANALYTICAL METHODS 

0.00033 per cc. for each degree centigrade. A correction 
should be made on this account if necessary. 

Blank Test. — As the acetic anhydride and sodium acetate 
may contain impurities which affect the result, it is neces- 
sary to make a blank test, using the same quantities of 
acetic anhydride, sodium acetate and water as in the analy- 
sis. It is not necessary to filter the solution of the melt 
in this case, but sufficient time must be allowed for the 
hydrolysis of the anhydride before proceeding with the 
neutralization. After neutralization it is not necessary to 
add more than 10 cc. of the N/l alkali (D), as this repre- 
sents the excess usually present after the saponification 
of the average soap lye crude. In determining the acid 
equivalent of the N/l NaOH, however, the entire amount 
taken in the analysis, 50 cc, should be titrated after dilu- 
tion with 300 cc. water free from carbon dioxide and with- 
out boiling. 

Determination of the Glycerol Value of the Acetylizable 
Impurities. — The total residue at 160° C. is dissolved in 
1 or 2 cc. of water, washed into the acetylizing flask and 
evaporated to dryness. Then add anhydrous sodium ace- 
tate and acetic anhydride in the usual amounts and proceed 
as described in the regular analysis. After correcting for 
the blank, calculate the result to glycerol. 

WAYS OF CALCULATING ACTUAL GLYCEROL CONTENT. 

(1) Determine the apparent percentage of glycerol in 
the sample by the acetin process as described. The result 
will include acetylizable impurities if any are present. 

(2) Determine the total residue at 160° C. 

(3) Determine the acetin value of the residue at (2) 
in terms of glycerol. 

(4) Deduct the result found at (3) from the percent- 
age obtained at (1) and report this corrected figure as 

^ 159 



■y^ 



SOAP-MAKING MANUAL 

glycerol. If volatile acetylizable impurities are present 
these are included in this figure. 

Trimethylenglycol is more volatile than glycerine and 
can therefore be concentrated by fractional distillation. An 
approximation to the quantity can be obtained from the 
spread between the acetin and bichromate results on such 
distillates. The spread multiplied by 1.736 will give the 
glycol. 

BICHROMATE PROCESS FOR GLYCEROL DETERMINATION. RE- 
AGENTS REQUIRED. 

(A) Pure potassium bichromate powdered and dried 
in air free from dust or organic vapors, at 110** to 120° C. 
This is taken as the standard. 

(B) Dilute Bichromate Solution. — 7.4564 grams of the 
above bichromate are dissolved in distilled water and the 
solution made up to one liter at 15.5* C. 

(C) Ferrous Ammonium Sulphate. — It is never safe 
to assume this salt to be constant in composition and it 
must be standardized against the bichromate as follows: 
dissolve 3.7282 grams of bichromate (A ) in 50 cc. of water. 
Add 50 cc. of 50 per cent, sulphuric acid (by volume), and 
to the cold undiluted solution add from a weighing bottle 
a moderate excess of the ferrous ammonium sulphate, and 
titrate back with the dilute bichromate (B). Calculate 
the value of the ferrous salt in terms of bichromate. 

(D) Silver Carbonate. — This is prepared as required 
for each test from 140 cc. of 0.5 per cent, silver sulphate 
solution by precipitation, with about 4.9 cc. N/l sodium 
carbonate solution (a little less than the calculated quan- 
tity of N/l sodium carbonate should be used as an excess 
to prevent rapid settling). Settle, decant and wash one by 
decantation. 

(£) Subacetate of Lead. — Boil a 10 per cent, solution 

160 



ANALYTICAL METHODS 

of pure lead acetate with an excess of litharge for one 
hour, keeping the volume constant, and filter while hot. 
Disregard any precipitate which subsequently forms. Pre- 
serve out of contact with carbon dioxide. 

(F) Potassium Ferricyanide. — A very dilute, freshly 
prepared solution containing about 0.1 per cent. 

THE METHOD. 

Weigh 20 grams of the glycerine, dilute to 250 cc. and 
take 25 cc. Add the silver carbonate, allow to stand, with 
occasional agitation, for about 10 minutes, and add a slight 
excess (about 5 cc. in most cases) of the basic lead acetate 
(£), allow to stand a few minutes, dilute with distilled 
water to 100 cc, and then add 0.15 cc. to compensate for 
the volume of the precipitate, mix thoroughly, filter through 
an air-dry filter into a suitable narrow-mouthed vessel, re- 
jecting the first 10 cc, and return the filtrate if not clear 
and bright. Test a portion of the filtrate with a little 
basic lead acetate, which should produce no further pre- 
cipitate (in the great majority of cases 5 cc. are ample, 
but occasionally a crude will be found requiring more, and 
in this case another aliquot of 25 cc. of the dilute glycerine 
should be taken and purified with 6 cc. of the basic acetate). 
Care must be taken to avoid a marked excess of basic 
acetate. 

Measure off 25 cc. of the clear filtrate into a flask or 
beaker (previously cleaned with potassium bichromate and 
sulphuric acid). Add 12 drops of sulphuric acid (1:4) 
to precipitate the small excess of lead as sulphate. Add 
3.7282 grams of the powdered potassium bichromate (A). 
Rinse down the bichromate with 25 cc. of water and let 
stand with occasional shaking until all the bichromate is 
dissolved (no reduction will take place in the cold). 

Now add 50 cc. of 50 per cent, sulphuric acid (by vol- 

161 



SOAP-MAKING MANUAL 

ume) and immerse the vessel in boiling water for two 
hours and keep protected from dust and organic vapors, 
such as alcohol, till the titration is completed. Add from 
a weighing bottle a slight excess of the ferrous ammonium 
sulphate (C), making spot tests on a porcelain plate with 
the potassium ferricyanide (F). Titrate back with the 
dilute bichromate. From the amount of bichromate re- 
duced calculate the percentage of glycerol. 

I gram glycerol = 7.4564 grams bichromate. 
1 gram bichromate = 0.13411 gram glycerol. 

The percentage of glycerol obtained above includes any 
oxidizable impurities present after the purification. A cor- 
rection for the non-volatile impurities may be made by 
running a bichromate test on the residue at 160** C. 

NOTES. 

(1) It is important that the concentration of acid in 
the oxidation mixture and the time of oxidation should 
be strictly adhered to. 

(2) Before the bichromate is ^ added to the glycerine 
solution it is essential that the slight excess of lead be pre- 
cipitated with sulphuric acid, as stipulated. 

(3) For crudes practically free from chlorides the 
quantity of silver carbonate may be reduced to one-fifth 
and the basic lead acetate to 0.5 cc. 

(4) It is sometimes advisable to add a little potassium 
sulphate to insure a clear filtrate. 

SAMPLING CRUDE GLYCERINE. 

The usual method of sampling crude glycerine hitherto 
has been by means of a glass tube, which is slowly lowered 
into the drum with the object of taking as nearly as pos- 
sible a vertical section of the glycerine contained in the 

1C2 



ANALYTICAL METHODS 

drum. This method has been found unsatisfactory, owing 
to the fact that in cold climates glycerine runs into the 
tube very slowly, so that, owing to the time occupied, it is 
impossible to take a complete section of the crude. An- 
other objection to the glass tube is that it fails to take 
anything approaching a correct proportion of any settled 
salt contained in the drum. 

The sampler which is illustrated herewith has been de- 
vised with the object of overcoming the objections to the 
glass tube as far as possible. It consists of two brass tubes, 
one fitting closely inside the other. A number of ports 
are cut out in each tube in such a way that when the ports 
are opened a continuous slot is formed which enables a 
complete section to be taken throughout the entire length 
of the drum. By this arrangement the glycerine fills into 
the sampler almost instantaneously. There are a number 
of ports cut at the bottom of the sampler which render it 
possible to take a proportion of the salt at the bottom of 
the drum. The instrument is so constructed that all the 
ports, including the bottom ones, can be closed simulta- 
neously by the simple action of turning the handle at the 
top; a pointer is arranged which indicates on a dial when 
the sampler is open or closed. In samplers of larger 
section (1 in.) it is possible to arrange a third motion 
whereby the bottom ports only are open for emptying, but 
in samplers of smaller dimensions (^ in.) this third mo- 
tion must be dispensed with, otherwise the dimensions of 
the ports have to be so small that the sampler would not 
be efficient. 

In using the sampler it is introduced into the drum with 
the ports closed, and when it has touched the bottom, the 
ports are opened for a second or two, then closed and with- 
drawn, and the sample discharged into the receiving vessel 
by opening the ports. When the drum contains salt which 

163 



SOAP-MAKING MANUAL 

has deposited, the ports must be opened before the sampler 
is pushed through the salt, thus enabling a portion to be in- 
cluded in the sample. It is, however, almost impossible to 
obtain a correct proportion of salt after it has settled in 
the drum and it is therefore recommended that the drum 
be sampled before any salt has deposited. A sampler 1 in. 
in diameter withdraws approximately 10 oz. from a 110- 
gal. drum. A sampler ^ in. in diameter will withdraw 
about 5 oz. 



164 



CHAPTER VII 

Standard Methods for the Sampling and Analysis of 

Commercial Fats and Oils^ 

The following report of the Comtnittee on Analysis of 
Commercial Fats and Oils of the Division of Industrial 
Chemists and Chemical Engineers of the American Chemi- 
cal Society was adopted April 14, 1919, by unanimous vote : 

W. D. Richardson, Chairman, J. R. Powell, 

Swift and Co., Chicago, 111. Armour Soap Works, Chi- 

R. W. Bailey, cage, 111. 

Stillwell and Gladding, New R. T. Quinn,* 

York City. Midland Chemical Co., Argo, 

W. T. Gascoyne, 111. 

W. J. Gascoyne and Co., Bal- Paul Rudnick, 

timore, Md. Armour and Co., Chicago, 111. 

I. Katz,* L. M. Tolman, 

Wilson and Co., Chicago, 111. Wilson and Co., Chicago, 111. 

A. LowENSTEiN,* E. Twitchell,* 

Morris and Co., Chicago, 111. Emery Candle Co., Cincin- 

H. J. MoRSisoN, nati, Ohio. 

Proctor and Gamble Co., J. J. Vollertsen, 

Ivorydale, Ohio. Morris and Co., Chicago, 111. 



•Resigned. 

Scope, Applicability and Limitations of the Methods. 

SCOPE. 

These methods are intended to aid in determining the 
commercial valuation of fats and fatty oils in their purchase 
and sale, based on the fundamental assumption commonly 
recognized in the trade, namely, that the product is true to 
name and is not adulterated. For methods for determining 
the identity of oils and fats, the absence of adulterants there- 
in and for specific tests used in particular industries, the 
chemist is referred to standard works on the analysis of fats 
and oils. 



* Approved by the Supervisory Committee on Standard Methods of 
Analysis of the American Chemical Society. 

165 



w 



SOAP-MAKING MANUAL 

APPLICABILITY. 

The methods are applicable in commercial transactions 
involving fats and fatty oils used in the soap, candle and 
tanning industries, to edible fats and oils and to fats and 
fatty oils intended for lubricating and burning purposes. 
The methods are applicable to the raw oils used in the 
varnish and paint industry with the exceptions noted under 
limitations, but special methods have not been included. 

LIMITATIONS. 

The methods have not been developed with special refer- 
ence to waxes (beeswax, carnauba wax, wool wax, etc.) 
although some of them may be found applicable to these 
substances. The Committee considers the Wijs method 
superior to the Hanus method for the determination of 
iodine number of linseed oil as well as other oils, although 
the Hanus method has been considered standard for this 
work for *some time and has been adopted by the American 
Society for Testing Materials and in various specifications. 
It has been customary to use the Hiibl method for the 
determination of iodine value of tung oil (China wood oil) 
but the Committee's work indicates that the Wijs method 
is satisfactory for this determination. 

Sampling. 

TANK CARS. 

1. Sampling While Loading — Sample shall be taken at 
discharge of pipe where it enters tank car dome. The total 
sample taken shall be not less than 50 lbs. and shall be a 
composite of small samples of abmit 1 pound each, taken 
at regular intervals during the entire period of loading. 

The sample thus obtained is thoroughly mixed and uni- 
form 3-lb. portions placed in air-tight 3-lb. metal containers. 
At least three such samples shall be put up, one for the 
buyer, one for the seller, and the third to be sent to a 

166 



L, iJ li T1 ■ 



STANDARD METHODS 

referee chemist in case of dispute. All samples are to be 
promptly and correctly labekd and seakd. 

2. Sampling from Car on Track^ — (a) When contents 
are solid.^ In this case the sample is taken by means of 
a large tryer measuring about 2 in. across and about V/2 
times the depth of the car in length. Several tryerfuls are 
taken vertically and obliquely toward the ends of the car 
until 50 lbs. are accumulated, when the sample is softened, 
mixed and handled as under (1). In case the contents of 
the tank car have assumed a very hard condition, as in 
Winter weather, so that it is impossible to insert the tryer, 
and it becomes necessary to soften the contents of the car by 
means of the closed steam coil (in nearly all tank cars the 
closed steam coil leaks) or by means of open steam in order 
to draw a proper sample, suitable arrangements must be 
made between buyer tnd seller for the sampling of the 
car after it is sufficiently softened, due consideration being 
given to the possible presence of water in the material in 
the car as received and also to the possible addition of 
water during the steaming. The Committee knows of no 
direct method for sampling a hard-frozen tank car of tallow 
in a satisfactory manner. 

(b) When contents are liquid. The sample taken is to 
be a 50-lb. composite made up of numerous small samples 
taken from the top, bottom and intermediate points by 
means of a bottle or metal container with removable stopper 
or top. This device attached to a suitable pole is lowered 
to the various desired depths, when the stopper or top is 
removed and the container allowed to fill. The 50-lb. sample 
thus obtained is handled as under (1). 



' Live steam must not be turned into tank cars or coils before 
samples are drawn, since there is no certain way of telling when 
coils are free from leaks. 

* If there is water present under the solid material this must be 
noted and estimated separately. 

167 



SOAP-MAKING MANUAL 

In place of the device described above, any sampler capable 
of taking a sample from the top, bottom, and center, or 
from a section through car, may be used. 

(c) When contents are in semi-solid condition, or when 
stearine has separated from liquid portions. In this case, a 
combination of (a) and (b) may be used or by agreement 
of the parties the whole may be melted and procedure (&) 
followed. 

BARRELS, TIERCES, CASKS, DRUMS, AND OTHER PACKAGES. 

All packages shall be sampled, unless by special agreement 
the parties arrange to sample a lesser number; but in any 
case not less than 10 per cent of the total nuniber shall be 
sampled. The total sample taken shall be at least 20 lbs. 
in weight for each 100 barrels, or equivalent. 

1. Barrels, Tierces and Casks — (a) When contents are 
solid. The small samples shall be taken by a tryer through 
the bunghole or through a special hole bored in the head or 
side for the purpose, with a 1-in. or larger auger. Care 
should be taken to avoid and eliminate all borings and chips 
from the sample. The tryer is inserted in such a way as to 
reach the head of the barrel, tierce, or cask. The large 
sample is softened, mixed and handled according to tank 
cars (1). 

(b) When contents are liquid. In this case use is made 
of a glass tube with constricted lower end. This is in- 
serted slowly and allowed to fill with the liquid, when the 
upper end is closed and the tube withdrawn, the contents 
being allowed to drain into the sample container. After 
the entire sample is taken it is thoroughly mixed and 
handled according to tank cars (1). 

(c) When contents are semd-solid. In this case the tryer 
or a glass tube with larger outlet is used, depending on the 
degree of fluidity. 

168 



i 



STANDARD METHODS 

(d) Very hard materials, such as natural and artiUcial 
stearines. By preference the barrels are stripped and 
samples obtained by breaking up contents of at least 10 per 
cent of the packages. This procedure is to be followed 
also in the case of cakes shipped in sacks. When shipped 
in the form of small pieces in sacks they can be sampled by 
grab sampling and quartering. In all cases the final pro- 
cedure is as outlined under tank cars (1). 

2. Drums — Samples are to be taken as under (1), use 
being made of the bunghole. The tryer or tube should be 
sufficiently long to reach to the ends of the drum. 

3. Other Packages — ^Tubs, pails and other small pack- 
ages not mentioned above are to be sampled by tryer or tube 
(depending on fluidity) as outlined above, the tryer or tube 
being inserted diagonally whenever possible. 

4. Mixed Lots and Packages — When lots of tallow or 
other fats are received in packages of various shapes and 
sizes, and especially wherein the fat itself is of variable 
composition, such must be left to the judgment of the 
sampler. If variable, the contents of each package should 
be mixed as thoroughly as possible and the amount of the 
individual samples taken made proportional to the sizes of 
the packages. 

Analysis. 

SAMPLE. 

The sample must be representative and at least three 
pounds in weight and taken in accordance with the stand- 
ard METHODS FOR THE SAMPLING OF COMMEROAL FATS AND 

OILS. It must be kept in an air-tight container, in a dark, 
cool place. 

Soften the sample if necessary by means of a gentle heat, 
taking care not to melt it. When sufficiently softened, mix 
the sample thoroughly by means of a mechanical egg beater 
or other equally effective mechanical mixer. 

169 



SOAP-MAKING MANUAL 

MOISTURE AND VOLATILE MATTER. 

Apparatus: Vacuum Oven — The Conmiittee Standard 
Oven. 

Description— The Standard F. A. C. Vacuum Oven has 
been designed with the idea of affording a simple and com- 
pact vacuum oven which will give as uniform temperatures 
as possible on the shelf. As the figure shows, it consists of 
an iron casting of rectangular sections with hinged front 
door made tight by means of a gasket and which can be 
lowered on opening the oven so as to form a shelf on which 
samples may be rested. The oven contains but one shelf 
• which is heated from above as well as below by means of 
resistance coils. Several thermometer holes are provided in 
order to ascertain definitely the temperature at different 
points on the shelf. In a vacuum oven where the heating 
is done almost entirely by radiation it is difficult to maintain 
uniform temperatures at all points, but the F. A. C. oven 
accomplishes this rather better than most vacuum ovens. 
Larger ovens containing more than one shelf have been 
tried by the Committee, but have been found to be lacking 
in temperature uniformity and means of control. The entire 
oven is supported by means of a 4-in. standard pipe which 
screws into the base of the oven and which in turn is sup- 
ported by being screwed into a blind flange of suitable di- 
ameter which rests on the floor or work table. 

Moisture Dish — A shallow, glass dish, lipped, beaker 
form, approximately 6 to 7 cm. diameter and 4 cm. deep, 
shall be standard. 

Determination — Weigh out 5 grams (=0.2 g. of the 
prepared sample into a moisture dish. Dry to constant 
weight in vacuo at a uniform temperature, not less than 15° 
C. nor more than 20° C. above the boiling point of water at 
the working pressure, which must not exceed 100 mm. of 
mercury.* Constant weight is attained when successive 

170 



__ I ^ 1^ 



STANDARD METHODS 




^/vekct Oft ftinoe9 



Standard Vacuum Oven 



171 



SOAP-MAKING MANUAL 

dryings for 1-hr. periods show an additional loss of not 
more that 0.05 per cent. Report loss in weight as mois- 
ture AND VOLAHLE MATTER.' 

The vacuum-oven method cannot be considered accurate 
in the case of fats of the coconut oil group containing free 
acid and the Committee recommends that it be used only for 
oils of this group when they contain less than 1 per cent 
free acid. In the case of oils of this group containing more 
than 1 per cent free acid, recourse should be had tempor- 
arily to the routine control method for moisture and vola- 
tile matter* until the Committee develops a more satisfactory 
method. 

The air-oven method cannot be considered even approxi- 
mately accurate in the case of the drying and semi-drying 
oils and those of the coconut oil group. Therefore, in the 
case of such oils as cottonseed oil, maize oil (corn oil), soy 
bean oil, linseed oil, coconut oil, palm kernel oil, etc., the 
vacuum-oven method should always be used, except in the 
case of fats of the coconut group containing more than 1 
per cent free acid, as noted above. 

INSOLUBLE IMPURITIES. 

Dissolve the residue from the moisture and volatile matter 



Boiling Point Boiling Point 

+ IS* C. 4- 20* C. 

67" C. 72^ C. 

65 - 70 

62 67 

60 65 

57 62 

53 58 

49 54 

■ Results comparable to those of the Standard Method may be ob- 
tained on most fats and oils by drying 5-g. portions of the sample, 
prepared and weighed as above, to constant weight in a well-con- 
structed and well-ventilated air oven held uniformly at a tempera- 
ture of 105* to 110® C. The thermometer bulb should be cloae to 
the sample. The definition of constant weight is the same as for the 
Standard Method. 

172 



* Boiling point of 


water at reduce 


Pressure 


Boiling Point 


Mm. Hg. 


to 1" C. 


lOO 


52" C. 


90 


50 


80 


47 


70 


45 


60 


42 


50 


38 


40 


34 



STANDARD METHODS 

determination by heating it on a steam bath with 50 cc. 
of kerosene. Filter the solution through a Gooch crucible 
properly prepared with asbestos/ wash the insoluble matter 
five times with 10-cc. portions of hot kerosene, and finally 
wash the residual kerosene out thoroughly with petroleum 
ether. Dry the crucible and contents to constant weight, as 
in the determination of moisture and volatile matter and 
report results as insoluble impurities. 

SOLUBLE MINERAL MATTER. 

Place the combined kerosene filtrate and kerosene wash- 
ings from the insoluble impurities determination in a plat- 
inum dish. Place in this an ashless filter paper folded in the 
form of a cone, ape^ up. Light the apex of the cone, where- 
upon the bulk of the kerosene burns quietly. Ash the resi- 
due in a muffle, to constant weight, taking care that the 
decomposition of alkaline earth carbonates is complete, and 
report the result as soluble mineral matter.' When the 
percentage of soluble mineral matter amounts to more than 
0.1 per cent, multiply the percentage by 10 and add this 
amount to the percentage of free fatty acids as determined.* 



•The following method is suggested by the Committee for routine 
control work: Weigh out 5- to 25-g. portions of prepared sample into 
a glass or aluminum (Cauticn: Aluminum soap may be formed) 
bejflcer or casserole and heat on a heavy asbestos board over burner 
or hot plate, taking care that the temperature of the sample does 
not go above 130" C. at any time. During the heating rotate the 
vessel gently on the board by hand to avoid sputterTng or too^ rapid 
evolution of moisture. The proper length of time of heating is 
judged by absence of rising bubbles of steam, by the absence of foam 
or by other signs known to the operator. Avoid overheating of sam- 
ple as indicated by smoking or darkening. Cool in desiccator and 
weigh. 

Bv co-operative work in several laboratrdes, the Committee has 
demonstrated that this method can be used and satisfactory results 
obtained on coconut oil even when a considerable percentage of free 
fatty acids is present, and the method is recommended for this pur- 
pose. Unfortunately on account of the very great personal factor 
mvolved, the Committee cannot establish this method as a preferred 
method. Nevertheless, after an operator has learned the technique 
of the method, it gives perfectly satisfactory results for ordinary 
oils and fats, butter, oleomargarine and coconut oil, and deserves 
more recognition than it has heretofore received. 

173 



SOAP-MAKING MANUAL 

FREE FATTY ACIDS. 

The ALCOHOL^" used shall be approximately 95 per cent 
ethyl alcohol, freshly distilled from sodium hydroxide, which 
with phenolphthalein gives a definite and distinct end-point. 

Determination — Weigh 1 to 15 g. of the prepared sample 
into an Erlenmeyer flask, using the smaller quantity in the 
case of dark-colored, high acid fats. Add 50 to 100 cc. hot, 
neutral alcohol, and titrate with iV/2, N/A or i\r/10 sodium 
hydroxide depending on the fatty acid content, using phenol- 
phthalein as indicator. Calculate to oleic acid, except that in 
the case of palm oil the results may also be expressed in 
terms of palmitic acid, clearly indicating the two methods of 
calculation in the report. In the case of coconut and palm 
kernel oils, calculate to and report in terms of lauric acid 
in addition to oleic acid, clearly indicating the two methods 
of calculation in the report. In the case of fats or greases 
containing more than 0.1 per cent of soluble mineral matter, 
add to the percentages of free fatty acids as determined 
10 times the percentage of bases in the soluble mineral 
matter as determined.' This addition gives the equivalent 
of fatty acids combined with the soluble mineral matter. 



" For routine contrcl work, filter paper is sometimes more con- 
venient than the prepared Gooch crucible, but must be very care- 
fully washed, especially around the rim, to remove the last traces of 
fat. 

8 For routine work, an ash may be run on the original fat, and the 
soluble mineral matter obtained by deducting the ash en the insolu- 
ble impurities from this. In this case the Gooch crucible should be 
prepared with an ignited asbestos mat so that the impurities may 
be ashed directly after being weighed. In all cases ignition should be 
to constant weight so as to insure complete decomposition of car- 
bonates. 

" See note on Soluble Mineral Matter following these methods. 
When the ash contains phosphates the factor 10 cannot be applied, 
but the bases consisting of calcium oxide, etc., must be determined, 
and the factor 10 applied to them. 

i** For routine work methyl or denatured ethyl alcohol of approxi- 
mately 95 per cent strengfth may be used. With these reagents the 
end-point is not sharp. 

174 



STANDARD METHODS 

TITER. 

Standard Thermometer — The thermometer is graduated 
at zero and in tenth degrees from 10° C to 65° C, with one 
auxiliary reservoir at the upper end and another between the 
zero mark and the 10° mark. The cavity in the capillary 
tube between the zero mark and the 10° mark is at least 1 
cm. below the 10° mark, the 10° mark is about 3 or 4 cm. 
above the bulb, the length of the thermometer being about 
2i7 cm. over all. The thermometer has been annealed for 75 
hrs. at 450° C. and the bulb is of Jena normal 16'" glass, or 
its equivalent, moderately thin, so that the thermometer will 
be quick-acting. The bulb is about 3 cm. long and 6 mm. in 
diameter. The stem of the thermometer is 6 mm. in diam- 
eter and made of the best thermometer tubing, with scale 
etched on the stem, the graduation is clear-cut and distinct, 
but quite fine. The thermometer must be certified by the 
U. S. Bureau of Standards. 

Glycerol Caustic Solution — Dissolve 250 g. potassium 
hydroxide in 1900 cc. dynamite glycerin with the aid of 
heat. 

Determination — Heat 75 cc. of the glycerol-caustic solu- 
tion to 150° C. and add 50 g. of the melted fat. Stir the 
mixture well and continue heating until the melt is homo- 
geneous, at no time allowing the temperature to exceed 150° 
C. Allow to cool somewhat and carefully add 50 cc. 30 
per cent sulfuric acid. Now add hot water and heat until 
the fatty acids separate out perfectly clear. Draw off the 
acid water and wash the fatty acids with hot water until free 
from mineral acid, then filter and heat to 130° C. as rapidly 
as possible while stirring. Transfer the fatty acids, when 
cooled somewhat, to a 1-in. by 4 -in. titer tube, placed in a 
16-oz. salt-mouth bottle of clear glass, fitted with a cork 
that is perforated so as to hold the tube rigidly when in 
position. Suspend the titer thermometer so that it can be 

175 



SOAP-MAKING MANUAL 

used as a stirrer and stir the fatty acids slowly (about 100 
revolutions per minute) until the mercury remains station- 
ary for 30 seconds. Allow the thermometer to hang quietly 
with the bulb in the center of the tube and report the 
highest point to which the mercury rises as the titer of the 
fatty acids. The titer should be made at about 20° C. for all 
fats having a titer above 30° C. and at 10° C. below the 
titer for all other fats. Any convenient means may be used 
for obtaining a temperature of 10° below the titer of the 
various fats. The committee recommends first of all a chill 
room for this purpose; second, an artificially chilled small 
chamber with glass window; third, immersion of the salt- 
mouth bottle in water or other liquid of the desired tem- 
perature. 

UNSAPONIFIABLE MATTER. 

Extraction Cylinder — The cylinder shall be glass- 
stoppered, graduated at 40 cc, 80 cc. and 130 cc, and of the 
following dimensions: diameter about l}i in., height about 
12 in. 

Petroleum Ether — Redistilled petroleum ether, boiling 
under 75° C, shall be used. A blank must be made by 
evaporating 250 cc. with about 0.25 g. of stearine or other 
hard fat (previously brought to constant weight by heating) 
and drying as in the actual determination. The blank must 
not exceed a few milligrams. 

Determination — Weigh 5 g. (±0.20 g.) of the prepared 
sample into a 200-cc. Erlenmeyer flask, add 30 cc. of re- 
distilled 95 per cent (approximately) ethyl alcohol and 5 cc. 
of 50 per cent aqueous potassium hydroxide, and boil the 
mixture for one hour under a reflux condenser. Transfer 
to the extraction cylinder and wash to the 40-cc. mark with 
redistilled 95 per cent ethyl alcohol. Complete the transfer, 
first with warm, then with cold water, till the total volume 
amounts to 80 cc. Cool the cylinder and contents to room 

176 



STANDARD METHODS 

temperature and add 50 cc. of petroleum ether. Shake 
vigorously for 6ne minute and allow to settle until both 
layers are clear, when the volume of the upper layer should 
be about 40 cc. Draw off the petroleum ether layer as 
closely as possible by means of a slender glass siphon into a 
separatory funnel of 500 cc. capacity. Repeat extraction at 
least four more times, using 50 cc. of petroleum ether each 
time. More extractions than five are necessary where the 
unsaponifiable matter runs high, say over 5 per cent, and 
also in some cases where it is lower than 5 per cent, but 
is extracted with difficulty. Wash the combined extracts in 
a separatory funnel three times with 25-cc. portions of 10 
per cent alcohol, shaking vigorously each time. Transfer 
the petroleum ether extract to a wide-mouth tared flask or 
beaker, and evaporate the petroleum ether on a steam bath 
in an air current. Dry as in the method for moisture and 
VOLATILE MATTER. Any blank must be deducted from the 
weight before calculating unsaponifiable matter. Test the 
final residue for solubility in 50 cc. petroleum ether at room 
temperature. Filter and wash free from the insoluble resi- 
due, if any, evaporate and dry in the same manner as be- 
fore. The Committee wishes to emphasize the necessity 
of thorough and vigorous shaking in order to secure 
accurate results. The two phases must be brought into the 
most intimate contact possible, otherwise low and disagree- 
ing results may be obtained. 

IODINE NUMBER — WIJS METHOD. 

Preparation of Reagents — Wijs Iodine Solution — Dis- 
solve 13.0 g. of resublimed iodine in one liter of C. P. glacial 
acetic acid and pass in washed and dried chlorine gas until 
the original thiosulfate titration of the solution is not quite 
doubled. The solution is then preserved in amber glass- 
stoppered bottles, sealed with paraffin until ready for use. 

Mark the date on which the solution is prepared on the 

177 



SOAP-MAKING MANUAL 

• 

bottle or bottles and do not use Wijs solution which is more 
than 30 days old. 

There should be no more than a slight excess of iodine, 
and no excess of chlorine. When the solution is made 
from iodine and chlorine, this point can be ascertained by 
not quite doubling the titration." 

The glacial acetic acid used for preparation of the Wijs 
solution should be of 99.0 to 99.5 per cent strength. In 
case of glacial acetic acids of somewhat lower strength, the 
Committee recommends freezing and centrifuging or dram- 
ing as a means of purification. 

N/10 Sodium Thiosulfate Solution — Dissolve 24.8 g. of 
C. P. sodium thiosulfate in recently boiled distilled water 
and dilute with the same to one liter at the temperature at 
which the titrations are to be made. 

Starch Paste — Boil 1 g. of starch in 200 cc. of distilled 
water for 10 min. and cool to room temperature. 

An improved starch solution may be prepared by auto- 
claving 2 g. of starch and 6 g. of boric acid dissolved in 200 
cc. water at 15 lbs. pressure for 15 min. This solution has 
good keeping qualities. 



"F. C. Mcllhiney, /. Am. Chem. Soc, 29 (1917). 1222, gives 
the following details for the preparation of the iodine monochloride 
solution : 

The preparation of the iodine monochloride solution presents no 
great difficulty, but it must be dene with care and accuracy in order 
to obtain satisfactory results. There must be in the scluticn no 
sensible excess either of iodine or niore particularly of chlorine, over 
that required to form the monochloride. This condition is mcst satis- 
factorily attained by dissolving in the whole of the acetic acid to be 
used the requisite quantity of iodine, using a gentle heat to assist 
the solution, if it is found necessary, setting aside a small portion 
of this solution, while pure and dry chlorine is passed into the re- 
mainder until the halogen content of the whole solution is doubled. 
Ordinarily it will be found that by passing the chlorine into the 
main part of the solution until the characteristic color of free iodine 
has just been discharged there will be a slight excess of chlorine 
which is corrected by the addition of the requisite amount of the 
unchlorinated portion until all free chlorine has been destroyed. A 
slight excess of iodine does little or no harm, but excess of chlorine 
Tiust be avoided. 

178 



STANDARD METHODS 

Potassium Iodide Solution — Dissolve 150 g. of potassium 
iodide in water and make up to one liter. 

iV/10 Potassium Bichromate — Dissolve 4.903 g. of C. P. 
potassium bichromate in water and make the volume up to 
one liter at the temperature at which titrations are to be 
made. 

The Committee calls attention to the fact that occasionally 
potassium bichromate is found containing sodium bichro- 
mate, although this is of rare occurrence. If the analyst 
suspects that he is dealing with an impure potassium 
bichromate, the purity can be ascertained by titration against 
re-sublimed iodine. However, this is unnecessary in the 
great majority of cases. 

Standardization of the Sodium Thio sulfate Solution — 
Place 40 cc. of the potassium bichromate solution, to which 
has been added 10 cc. of the solution of potassium iodide, 
in a glass-stoppered flask. Add to this 5 cc. of strong 
hydro-chloric acid. Dilute with 100 cc. of water, and allow the 
A^/10 sodium thiosulfate to flow slowly into the flask until 
Ihe yellow color of the Iquid has almost disappeared. Add 
a few drops of the starch paste, and with constant shaking 
continue to add the iV^/10 sodium thiosulfate solution until 
the blue color just disappears. 

Determination — Weigh accurately from 0.10 to 0.50 g. 
(depending on the iodine number) of the melted and filtered 
sample into a clean, dry, 16-oz. glass-stoppered bottle con- 
taining 15-20 cc. of carbon tetrachloride or chloroform. Add 
25 cc. of iodine solution from a pipette, allowing to drain 
for a definite time. The excess of iodine should be from 
50 per cent to 60 per cent of the amount added, that is, 
from 100 per cent to 150 per cent of the amount absorbed. 
Moisten the stopper with a 15 per cent potassium iodide so- 
lution to prevent loss of iodine or chlorine but guard against 
an amount sufficient to run down inside the bottle. Let 

179 



SOAP-MAKING MANUAL 

the bottle stand in a dark place for J^ hr. at a uniform 
temperature. At the end of that time add 20 cc. of 15 per 
cent potassium iodide solution and 100 cc. of distilled water. 
Titrate the iodine with N/IO sodium thiosulfate solution 
which is added gradually, with constant shaking, until the 
yellow color of the solution has almost disappeared. Add 
a few drops of starch paste and continue titration until the 
blue color has entirely disappeared. Toward the end of the 
reaction stopper the bottle and shake violently so that any 
iodine remaining in solution in the tetrachloride or chloro- 
form may be taken up by the potassium iodide solution. 
Conduct two determinations on blanks which must be run 
in the same manner as the sample except that no fat is used 
in the blanks. Slight variations in temperature quite appre- 
ciably affect the titer of the iodine solution, as acetic acid 
has a high coefficient of expansion. It is, therefore, essen- 
tial that the blanks and determinations on the sample be 
made at the same time. The number of cc. of standard 
thiosulfate solution required by the blank, less the amount 
used in the determination, gives the thiosulfate equivalent 
of the iodine absorbed by the amount of sample used in the 
determination. Calculate to centigrams of iodine absorbed 
by 1 g. of sample (= per cent iodine absorbed). 

Determination, Tung Oil — Tung oil shows an erratic 
behavior with most iodine reagents and this is particularly 
noticeable in the case of the Hanus reagent which is entirely 
unsuitable for determining the iodine number of this oil 
since extremely high and irregular results are obtained. 
The Hiibl solution shows a progressive absorption up to 24 
hrs. and probably for a longer time but the period required 
is entirely too long for a chemical determination. The Wijs 
solution gives good results if the following precautions are 
observed : 

Weigh out 0.15 ± 0.05 g., use an excess of 55 ± 3 per 

180 



STANDARD METHODS 

cent Wijs solution. Conduct the absorption at a temperature 
of 20-25** C. for 1 hr. In other respects follow the instruc- 
tions detailed above. 

SAPONIFICATION NUMBER (KOETTSTORFER NUMBER). 

Preparation of Reagents. iV/^ Hydrochloric Acid — 
Carefully standardized. 

Alcoholic Potassium Hydroxide Solution — Dissolve 40 g. 
of pure potassium hydroxide in one liter' of 95 per cent re- 
distilled alcohol (by voliune). The alcohol should be re- 
distilled from potassium hydroxide over which it has been 
standing for some time, or with which it has been boiled for 
some time, using a reflux condenser. The solution must be 
clear and the potassium hydroxide free from carbonates. 

Determination — Weigh accurate about 5 g. of the filtered 
sample into a 250 to 300 cc. Erlenmeyer flask. Pipette S§ 
cc. of the alcoholic potassium hydroxide solution into the 
flask, allowing the pipette to drain for a definite time. Con- 
nect the flask with an air condenser and boil until the fat 
is completely saponified (about 30 minutes). Cool and 
titrate with the N/2 hydrochloric acid, using phenolphthalein 
as an indicator. Calculate the Koettstorfer number (mg. 
of potassiimi hydroxide required to saponify 1 g. of fat). 
Conduct 2 or 3 blank determinations, using the same pipette 
and draining for the same length of time as above. 

melting point. 

Apparatus — Capillary tubes made from 5 mm. inside di- 
ameter thin-walled glass tubing drawn out to 1 mm. inside 
diameter. Length of capillary part of tubes to be about 
5 cm. Length of tube over all 8 cm. 

Standard thermometer graduated in tenths of a degree. 

6oo cc. beaker. 

Determination — The sample should be clear when melted 

181 



SOAP-MAKING MANUAL 

and entirely free from moisture, or incorrect results will be 
obtained. 

Melt and thoroughly mix the sample. Dip three of the 
capillary tubes above described in the oil so that the fat in 
the tube stands about 1 cm. in height. Now fuse the capil- 
lary end carefully by means of a small blast flame and 
allow to cool. These tubes are placed in a refrigerator over 
night at a temperature of from 40 to 50** F. They are then 
fastened by means of a rubber band or other suitable means 
to the bulb of a thermometer graduated in tenths of a de- 
gree. The thermometer is suspended in a beaker of water 
(which is agitated by air or other suitable means) so that 
the bottom of the bulb of the thermometer is immersed to 
a depth of about 3 cm. The temperature of the water is 
increased gradually at the rate of about 1° per minute. 

The point at which the sample becomes opalescent is first 
noted and the heating continued until the contents of the 
tube becomes uniformly transparent. The latter tempera- 
ture is reported as the melting point. 

Before finally melting to a perfectly clear fluid, the sample 
becomes opalescent and usually appears clear at the top, 
bottom, and sides before becoming clear at the center. The 
heating is continued until the contents of the tube become 
uniformly clear and transparent. This temperature is re- 
ported as the melting point.^^ It is usually only a fraction 
of a degree above the opalescent point noted. The ther- 
mometer should be read to the nearest ^° C, and in addi- 
tion this temperature may be reported to the nearest degree 
Fahrenheit if desired. 

CLOUD TEST. 

Precautions — (1) The oil must be perfectly dry, because 



1* The melting point of oils may be determined in general according 
to the above procedure, taking into consideration the lower tempera- 



ture required. 

182 



1 



STANDARD METHODS 

the presence of moisture will produce a turbidity before the 
clouding point is reached. 

(2) The oil must be heated to 150° C. over a free flame, 
immediately before making the test. 

(3) There must not be too much discrepancy between the 
temperature of the bath and the clouding point of the oil. 
An oil that will cloud at the temperature of hydrant water 
should be tested in a bath of that temperature. An oil that 
will cloud in a mixture of ice and water should be tested in 
such a bath. An oil that will not cloud in a bath of ice 
and water must be tested in a bath ©f salt, ice, and water. 

Determination — The oil is heated in a porcelain casserole 
over a free flame to 150° C, stirring with the thermometer. 
As soon as it can be done with safety, the oil is transferred 
to a 4 oz. oil bottle, which must be perfectly dry. One and 
one-half ounces of the oil are sufficient for the test. A dry 
centigrade thermometer is placed in the oil, and the bottle 
is then cooled by immersion in a suitable bath. The oil is 
constantly stirred with the thermometer, taking care not to 
remove the thermometer from the oil at any time during 
the test, so as to avoid stirring air bubbles into the oil. 
The bottle is frequently removed from the bath for a few 
moments. The oil must not be allowed to chill on the 
sides and bottom of the bottle. This is effected by constant 
and vigorous stirring with the thermometer. As soon as 
the first permanent cloud shows in the body of the oil, the 
temperature at which this cloud occurs is noted. 

With care, results concordant to within ^° C. can be ob- 
tained by this method. A Fahrenheit thermometer is some- 
times used because it has become customary to report re- 
sults in degrees Fahrenheit. 

The oil must be tested within a short time after heating 
to 150° C. and a re-test must always be preceded by re- 
heating to that temperature. The cloud point should be 

183 



SOAP-MAKING MANUAL 

approached as quickly as possible, yet not so fast that the 
oil is frozen on the sides or bottom of the bottle before the 
cloud test is reached. 

Notes on the Above Methods. 

SAMPLING. 

The standard size of sample adopted by the committee is 
at least 3 lbs. in weight. The committee realizes that this 
amount is larger than any samples usually furnished even 
when representing shipments of from 20,000 to 60,000 lbs., 
but it believes that the requirement of a larger sample is 
desirable and will work toward uniform and more con- 
cordant results in analysis. It will probably continue to be 
the custom of the trade to submit smaller buyers* samples 
than required by the committee, but these are to be consid- 
ered only as samples for inspection and not for analysis. The 
standard analytical sample must consist of 3 lbs. or more. 

The reasons for keeping samples in a dark, cool place are 
obvious. This is to prevent any increase in rancidity and 
any undue increase in free fatty acids. In the case of many 
fats the committee has found in its co-operative analjrtical 
work that free acid tends to increase very rapidly. This 
tendency is minimized by low temperatures. 

MOISTtJRE AND VOLATILE MATTER. 

After careful consideration the committee has decided that 
moisture is best determined in a vacuum oven of the design 
which accompanies the above report. Numerous results on 
check samples have confirmed the committee's conclusions. 
The oven recommended by the committee is constructed on 
the basis of well-known principles and it is hoped that this 
type will be adopted generally by chemists who are called 
upon to analyze fats and oils. The experiments of the com- 
mittee indicate that it is a most difficult matter to design a 
vacuum oven which will produce uniform temperatures 

184 



m 



STANDARD METHODS 

throughout; and one of the principal ideas in the design 
adopted is uniformity of temperature over the entire single 
shelf. This idea has not quite been realized in practice but, 
nevertheless, the present design approaches much closer to 
the ideal than other vacuum ovens commonly used. In the 
drawing the essential dimensions are those between the heat- 
ing units and the shelf and the length and breadth of the 
outer casting. The standard Fat Analysis Committee Oven 
(F. A. C Oven) can be furnished by Messrs. E. H. Sargent 
& Company, 125 West Lake street, Chicago. 

The committee realizes that for routine work a quicker 
method is desirable and has added one such metliod and 
has also stated the conditions under which comparable re- 
sults can be obtained by means of the ordinary well-venti- 
lated air oven held at 105 to 110** C. However, in accord- 
ance with a fundamental principle adopted by the committee 
at its first meeting, only one standard method is adopted and 
declared official for each determination. 

The committee realizes that in the case of all methods 
for determining moisture by means of loss on heating there 
may be a loss due to volatile matter (especially fatty acids) 
other than water. The title of the determination moisture 
AND VOLATILE MATTER indicates this idea, but any considerable 
error from this source may occur only in the case of high 
acid fats and oils and particularly those containing lower 
fatty acids such as coconut and palm kernel oil. In the 
case of extracted greases which have not been properly puri- 
fied, some of the solvent may also be included in the mois- 
ture and volatile matter determination, but inasmuch as the 
solvent, usually a petroleum product, can only be considered 
as foreign matter, for commercial purposes, it is entirely 
proper to include it with the moisture. 

The committee has also considered the various distillation 
methods for the determination of moisture in £ats and oils, 

US 



SOAP-MAKING MANUAL 

but since according to the fundamental principles which it 
was endeavoring to follow it could only standardize one 
method, it was decided that the most desirable one on the 
whole was the vacuum-oven method as given. There are 
cases wherein a chemist may find it desirable to check a 
moisture determination or investigate the moisture content 
of a fat or oil further by means of one of the distillation 
methods. 

However, in co-operative work the distillation method in 
various types of apparatus has not yielded satisfactory re- 
sults. The difficulties appear to be connected with a proper 
choice of solvent and particularly with the tendency of 
drops of water to adhere to various parts of the glass ap- 
paratus instead of passing on to the measuring device. 
When working on coconut oil containing a high percentage 
of free fatty acids, concordant results could not be obtained 
by the various members of the committee when working 
with identical samples, solvents and apparatus. 

On the other hand, the committee found by individual 
work, co-operative work and collaborative work by several 
members of the committee in one laboratory, that the old, 
well-known direct heating method (which the committee has 
designated the hot plate method) yielded very satisfactory 
results on all sorts of fats and oils including emulsions such 
as butter and oleomargarine and even on coconut oil sam- 
ples containing 15 to 20 per cent free fatty acids and 5 to 6 
per cent of moisture. Unfortunately, this method depends 
altogether on the operator's skill and while the method may 
be taught to any person whether a chemist or not so that 
he can obtain excellent results with it, it is difficult to give 
a sufficiently, complete description of it so that any chemist 
anywhere after reading the description could follow it suc- 
cessfully. The method is undoubtedly worthy of much con- 
fidence in careful hands. It is quick, accurate and reliable. 

186 



STANDARD METHODS 

It is probably the best single method for the determination 
of moisture in all sorts of samples for routine laboratory 
work. On account of this fact the committee desires to 
announce its willingness to instruct any person in the proper 
use of the method who desires to become acquainted with it 
and who will visit any committee member's laboratory. 

INSOLUBLE IMPURITIES. 

This determination, the title for which was adopted after 
careful consideration, determines the impurities which have 
generally been known as dirt, suspended matter, suspended 
solids, foreign solids, foreign matter, etc., in the past. The 
first solvent recommended by the committee is hot kerosene 
to be followed by petroleum ether kept at ordinary room 
temperature. Petroleum ether, cold or only slightly warm, 
is not a good fat and metallic soap solvent, whereas hot 
kerosene dissolves these substances readily, and for this 
reason the committee has recommended the double solvent 
method so as to exclude metallic soaps which are determined 
below as soluble mineral matter. 

SOLUBLE MINERAL MATTER. 

Soluble mineral matter represents mineral matter com- 
bined with fatty acids in the form of soaps in solution in 
the fat or oil. Formerly, this mineral matter was often de- 
termined in combination by weighing the separated metallic 
soap or by weighing it in conjunction with the insoluble im- 
purities. Since the soaps present consist mostly of lime 
soap, it has been customary to calculate the lime present 
therein by taking 0.1 the weight of the total metallic soaps. 
The standard method as given above is direct and involves 
no calculation. The routine method given in the note has 
been placed among the methods for the reason that it is 
used in some laboratories, but has not been adopted as a 
standard method in view of the fact that the committee has 

187 



SOAP-MAKING MANUAL 

made it a rule to adopt only one standard method. It 
should be pointed out, however, that the method cannot be 
considered accurate for the reason that insoluble impurities 
may vary from sample to sample to a considerable extent 
and the error due to the presence of large particles of in- 
soluble impurities is thus transferred to the soluble mineral 
matter. The committee has found one type of grease 
(naphtha bone grease) which shows most unusual charac- 
teristics. The type sample contains 4.3 per cent soluble 
mineral matter by the committee method which would be 
equivalent to 43.0 per cent free fatty acid. The kerosene 
and gasoline filtrate was particularly clear, nevertheless the 
ash was found to contain 36.43 per cent PaOa equivalent to 
79.60 per cent of Ca«(P04)2 and 9.63 per cent of FejOs. 
The method, therefore, determines the soluble mineral mat- 
ter in this case satisfactorily but the factor 10 is not ap- 
plicable for calculating the fatty acids combined therewith. 
It is necessary, therefore, in order to determine the fatty 
acids combined with soluble mineral matter in the original 
sample to determine the actual bases in the soluble mineral 
matter as obtained by ashing the kerosene and gasoline fil- 
trate. To the bases so determined the factor 10 can then 
be applied. 

FREE FATTY ACID. 

The fatty acid method adopted is sufficiently accurate for 
commercial purposes. In many routine laboratories the fat 
or oil is measured and not weighed, but the committee rec- 
ommends weighing the sample in all cases. For scientific 
purposes the result is often expressed as "acid nuralber," 
meaning the number of milligrams of KOH required to 
neutralize the free acids in one gram of fat, but the com- 
mercial practice has been, and is, to express the fatty acids 
as oleic acid or in the case of palm oil, as palmitic acid, 
in some instances. The tommittee sees no objection to the 

188 



STANDARD METHODS 

continuation of this custom so long as the analytical report 
clearly indicates how the free acid is expressed. For a 
more exact expression of the free acid in a given fat, the 
committee recommends that the ratio of acid ntmiber to 
saponification number be used. This method of expressing 
results is subject to error when unsaponifiable fatty matter 
is present, since the result expresses the ratio of free fatty 
acid to total saponifiable fatty matter present. 

TITER. 

At the present time the prices of gycerol and caustic pot- 
ash are abnormally high, but the committee has considered 
that the methods adopted are for normal times and normal 
prices. For routine work during the period of high prices 
the following method may be used for preparing the fatty 
acids and is recommended by the committee: 

Fifty grams of fat are saponified with 60 cc. of a solution 
of 2 parts of methyl alcohol to 1 of 50 per cent NaOH. 
The soap is dried, pulverized and dissolved in 1000 cc. of 
water in a porcelain dish and then decomposed with 25 cc. 
of 75 per cent sulphuric acid. The fatty acids are boiled 
until clear oil is formed and then collected and settled in a 
150-cc. 'beaker and filtered into a 50-cc. beaker. They are 
then heated to 130* C as rapidly as possible with stirring, 
and transferred, after they have cooled somewhat, to the 
usual 1-in. by 4-in. titer tube. 

The method of taking the titer, including handling the 
thermometer, to be followed is the same as that described in 
the standard method. Even at present high prices many 
laboratories are using the glycerol-caustic potash method 
for preparing the fatty acids, figuring that the saving of 
time more than compensates for the extra cost of the re- 
agents. Caustic soda cannot be substituted for caustic pot- 
ash in the glycerol method. 

189 



SOAP-MAKING MANUAL 

UNSAPONIFIABLE MATTER. 

The committee has considered unsaponifiable matter to 
include those substances frequently found dissolved in fats 
and oils which are not saponified by the caustic alkalies and 
which at the same time are soluble in the ordinary fat 
solvents. The term includes such substances as the higher 
alcohols, such as cholesterol which in found in animal fats, 
phytosterol found in some vegetable fats, paraffin and petro- 
leum oils, etc. Unsaponifiable matter should not be con- 
fused in the lay mind with insoluble impurities or soluble 

MINERAL MATTER. 

The method adopted by the committee has been selected 
only after the most careful consideration of other methods, 
such as the dry extraction method and the wet method mak- 
ing use of the separatory funnel. At first consideration the 
dry extraction process would seem to offer the best basis 
for an unsaponifiable matter method, but in practice it has 
been found absolutely impossible* for diflFerent analysts to 
obtain agreeing results when using any of the dry extrac- 
tion methods proposed. Therefore, this method had to be 
abondoned after numerous trials, although several members 
of the committee strongly favored it in the beginning. 

Iodine Number — The iodine number adopted by the com- 
mittee is that determined by the well-known Wijs method. 
This method was adopted after careful comparison with the 
Hanus and Hiibl methods. The Hiibl method was elimi- 
nated from consideration almost at the beginning of the com- 
mittee's work for the reason that the time required for 
complete absorption of the iodine is unnecessarily long and, 
in fact, even after absorption has gone on over night, it is 
apparently not complete. In the case of the Hanus and Wijs 
methods complete absorption takes place in from 15 minutes 
to an hour, depending on conditions. Formerly, many 
chemists thought the Hanus solution rather easier to prepare 

?90 



STANDARD METHODS 

than the Wijs solution, but the experience of the committee 
was that the Wijs solution was no more difficult to prepare 
than the Hanus. Furthermore, absorption of iodine from 
the Wijs solution appeared to take place with greater 
promptness and certainty than from the Hanus and was 
complete in a shorter time. Results by the Wijs method 
were also in better agreement in the case of oils showing 
high iodine absorption than with the Hanus solution and 
showed a slightly higher iodine absorption for the same 
length of time. However, the difference was not great. 
The committee investigated the question of substitution 
since it has been suggested that in case of the Wijs solution 
substitution of iodine in the organic molecule might occur, 
and found no evidence of this in the time required for 
the determination, namely, J^ hr., or even for a somewhat 
longer period. One member of the committee felt that it 
was not desirable to introduce the Wijs method into these 
standard methods since the Hanus method was already 
standardized by the Association of Official Agricultural 
Chemists, but the committee felt that it must follow the 
principle established at the commencement of its work, 
namely, that of adopting the method which appeared to 
be the best from all standpoints, taking into consideration 
accuracy, convenience, simplicity, time, expense, etc., with- 
out allowing precedent to have the deciding vote. 

Iodine Number, Tung Oil — ^The committee has made an 
extensive study of the application of the Wijs method to 
the determination of iodine value in the case of tung oil 
with the result that it recommends the method for this oil 
but has thought it desirable to limit the conditions under 
which the determination is conducted rather narrowly, al- 
though reasonably good results are obtained by the com- 
mittee method without making use of the special limitations. 

The co-operative work of the committee and the special 

191 



SOAP-MAKING MANUAL 

investigations conducted by individual members bring out 
the following points : 

Influence of Temperature — From 16** C. to 30* C. there 
is a moderate increase in the absorption, but above 30** the 
increase is rather rapid so that it was thought best to 
limit the temperature in the case of tung oil to 20** to 25** C. 

Influence of Time — ^The absorption increases with the 
time but apparently complete absorption, so far as unsat- 
urated bonds are concerned, occurs well within one hour's 
time. Consequently, one hour was set as the practical limit. 

Influence of Excess — ^The excess of iodine solution also 
tends to increase the iodine number, hence the Committee 
thought it necessary to limit the excess rather rigidly to 
55 ± 3 per cent, although with greater latitude results were 
reasonably good. 

Influence of Age of Solution — ^Old solutions tend to give 
low results although up to 2 mo. no great differences were 
observed. Nevertheless, it was thought best to limit the age 
of the solution to 30 days — long enough for all practical 
purposes. 

Amount of Sample — ^As a practical amount of sample to 
be weighed out the Committee decided on 0.15 g. with a 
tolerance of 0.05 g. in either direction according to prefer- 
ence. In other words, the amount of sample to be taken 
for the determination to be from 0.1 to 0.2 g. in the discre- 
tion of the analyst. 

The Committee's study of the Htibl method which has 
been adopted by the Society for Testing Materials in the 
case of tung oil indicates that this method when applied 
to tung oil is subject to the same influences as the Wijs 
method and it has the additional very serious disadvantage 
of requiring a long period of time for absorption which 
cannot be considered reasonable for a modem anal3rtical 
method. When using the Hflbl solution, the absorption is 

192 



STANDARD METHODS 

not compkte in the case of tung oil at 3, 7, 18 or even 24 
lirs. 

The Hanus method in the case of tung oil gives very 
high and erratic restilts, as high as 180 to 240 in ordinary 
cases for an oil whose true iodine nun4>er is ahout 165. 

MELTING POINT. 

A melting point is the temperature at which a solid sub- 
stance assumes the liquid condition. If the solid is a pure 
substance in the crystalline conditicm the melting point is 
sharp and well defined for any given pressure. With in- 
creased pressure the melting point is lowered or raised, de- 
pending on whether the substance contracts or expands in 
melting. The lowering or raising of the melting point with 
pressure is very slight and ordinarily is not taken into 
consideration. Melting-point determinations are commonly 
carried out tmder ordinary atmospheric pressures without 
correction. The general ~^ect of soluble impurities is to 
lower the melting point, and this holds true whether the 
impurity has a higher or lower melting point than the pure 
substance (solvent). Thus if a small amount of stearic acid 
be added to liquid palmitic acid and the solution frozen, the 
melting point of this solid will be lower than that of palmitic 
acid. Likewise the melting point of stearic acid is lowered 
by the addition of a small amount of palmitic add. A eutec- 
tic mixture results when two components solidify simulta- 
neously at a definite temperature. Such a mixture has a 
constant melting point and because of this and also because 
both solid and liquid phases have the same composition, 
eutectic mixtures were formerly looked upon as com- 
potmds. The phenomenon of double melting points has 
been observed in the case of a number of glycerides. Such 
a glyceride when placed in the usual capillary tube and 
subjected to increasing temperature quickly resolidifies only 

M3 



SOAP-MAKING MANUAL 

to melt again and remain melted at a still higher tempera- 
ture. This phenomenon has not yet been sufficiently in- 
vestigated to afford a satisfactory explanation. 

Non-crystalline substances such as glass, sealing wax and 
various other waxes and wax mixtures, and most colloidal 
substances do not exhibit a sharp melting point, but under 
the application of heat first soften very gradually and at a 
considerably higher temperature melt sufficiently to flow. 
This phenomenon of melting through a long range of tem- 
perature may be due to the amorphous nature of the sub- 
stance or to the fact that it consists of a very large number 
of components of many different melting points. 

The fats and oils of natural origin, that is, the animal and 
vegetable fats and oils, consist of mixtures of glycerides and, 
generally speaking, of a considerable number of such com- 
ponents. These components are crystalline and when sep- 
arated in the pure state have definite melting points, al- 
though some exhibit the phenomenon of double melting 
point. For the most part the naturally occurring glycerides 
are mixed glycerides. In the natural fats and oils there are 
present also certain higher alcohols, of which cholesterol is 
characteristic of the animal fats and oils and phytosterol of 
many of the vegetable fats and oils. In addition to the 
crystalline glycerides and the higher alcohols present in 
neutral fats, there are in fats of lower grade, fatty acids, 
which are crystalline, and also various non-crystalline im- 
purities of an unsaponifiabe nature, and the presence of 
these impurities tends to lower the melting point. They 
also tend to induce undercooling and when the liquid fat or 
oil is being chilled for purposes of solidification or in de- 
termination of titer. 

The presence of water, especially when this is thoroughly 
mixed or emulsified with a fat or oil, also influences the 
melting point to a marked extent, causing the mixture to 

194 



STANDARD METHODS 

melt through a longer range of temperatures than would be 
the case if the water were absent. This is particularly true 
of emulsified fats and oils, such as butter and oleomargarine, 
both of which contain, besides water, the solids naturally 
present in milk or cream and including casein, milk sugar, 
and salts. The melting-point method recommended by the 
Committee is not applicable to such emulsions or other 
watery mixtures and the Committee has found it impossible 
to devise an accurate method for making softening-point or 
melting-point determinations on products of this nature. 
Not only the amount of water present but also the fineness 
of its particles, that is, its state of subdivision and distri- 
bution, in a fat or oil influences the softening point or melt- 
ing point and causes it to vary widely in different samples. 

As a consequence of the foregoing facts, natural fats and 
oils do not exhibit a definite melting point, composed as they 
are of mixtures of various crystalline glycerides, higher 
alcohols, fatty acids, and non-cystalline substances. There- 
fore, the term melting point when applied to them requires 
further definition. They exhibit first a lower melting point 
(the melting point of the lowest melting component) or 
what might be called the softening point and following this 
the fat softens through a shorter or longer range of tem- 
perature to the final melting point at which temperature the 
fat is entirely liquid. This is the melting point determined 
by the Committee's melting-point method. The range be- 
tween the softening point and the final melting point varies 
greatly with the different fats and oils depending on their 
chemical components, the water associated with them, 
emulsification, etc. In the case of coconut oil the range 
between softening point and final melting point is rather 
short; in the case of butter, long. Various methods have 
been devised to determine the so-called melting point of fats 
and oils. Most of these methods, however, determine, not 

19S 



7 



SOAP-MAKING MANUAL 

the melting point, but the softemng point or the flow point 
of the fat and the great difikulty has been in the past to 
devise a method which would determine even this point 
with reasonable accuracy and so that results could be easily 
duplicated. It has been the aim of the Conunittee to 
devise a simple method for the determination of the melting 
point of fats and oils, but it should be understood that the 
term melting point in the scientific sense is not applicable to 
natural fats and oils. 



196 



PLANT AND 
MACHINERY 

Illustrations of machinery and layouts 
of the plant of a modern soap-making 

establishment. 



197 



PLANT AND MACHINERY 



UAAAAAA' 

Hoist, Lye Tank, etc. 



Melting- Out Trough 



SOAP-MAKING MANUAL 




PLANT AND MACHINERY 




Dbving Back 



HORIZONTAL UBUTCHER 



PLANT AND MACHINERY 



Cutting Table 



SOAP-MAKING MANUAL 



Automatic Power Cutting Table 



Automatic Pbbss (Laundry) 



PLANT AND MACHINERY 



Cutting Table (Hand) 



Carton Wrappinc Machine 



SOAP-MAKING MANUAL 



Soap Powder Box 



Scouring Soap Press 



PLANT AND MACHINERY 



SOAP-MAKING MANUAL 



FtuFFV Soap Powder Eqijipiient 



PLANT AND MACHINERY 



Soap Powder Mixer 



Soap Powder Miu. 



SOAP-MAKING MANUAL 



PLANT AND MACHINERY 



ts 



^ 



SOAP-MAKING MANUAL 



Toilet Soap Mnx 



Ton£T Soap Mill 



PLANT AND MACHINERY 



Horizontal Cbippeb Aualgamatob (Impboted) 



SOAP-MAKING MANUAL 




Press (Lettering on Pbi^ss (Foot) 
4 Sides of Cake) 



PLANT AND MACHINERY 



Automatic Press (Toilet) Multiple Cake Cutter 



SOAP-MAKING MANUAL 




"^ 



216 



PLANT AND MACHINERY 



SOAP-MAKING MANUAL 




218 



Z 

< 



Appendix 



Tables marked * are taken from the German Year 
Book for Soap Industry. 



219 



SOAP-MAKING MANUAL 

(U. S. BUREAU OF STANDARDS) 
THE METRIC SYSTEM. 

The fundamental unit of the metric system is the meter 
(the imit of length). From this the units of mass 
(gram) and capacity (liter) are derived. All other units 
are the decimal sub-divisions or multiples of these. These 
three units are simply related, so that for all practical 
purposes the volume of one kilogram of water (one liter) 
is equal to one cubic decimeter. 



Prefixes. Meaning. 


Units. 


Milli- = one thousandth 1-1000 .001 




Centi- = one hundredth 1-100 .01 
Deci- = one tenth 1-10 .1 


Meter for length. 


Unit = one 1. 


Gram for mass. 


Deka- = ten 10-1 10. 
Hecto- = one hundred 100-1 100. 


Liter for capacity. 


Kilo- = one thousand 1000-1 1000. 





The metric terms are formed by combining the words 
"Meter," "Gram" and "Liter" with the six numerical 
prefixes. 



10 milli-meters mm 
10 centi-meters 
10 deci-meters 

10 meters 

10 deka-meters 
10 hecto-meters 



Length 

1 centi-meter cm 

1 deci-meter dm 

1 meter (about 40 inches) m 

1 deka-meter dkm 

1 hecto-meter h m 

1 kilo-meter (about H mile) . .km 

220 



^ 



APPENDIX 

Mass. 

10 milli-grams. m g = 1 centi-gram eg 

10 centi-grams = 1 deci-gram — d g 

ictff 10 deci-grams = 1 gram (about 15 grains) g 

nasi 10 grams = 1 deka-gram dkg 

10 Deka-grams = 1 hecto-gram h g 

10 hecto-grams = 1 kilo-gram (about 2 pounds) .kg 



id 



Capacity. 

10 milli-liters ...ml = 1 centi-liter c 1 

10 ccnti-litcrs = 1 deci-litcr d 1 

10 dcci-litcrs = 1 liter (about 1 quart) 1 

10 liters = 1 deka-liter dkl 

10 deka-liters = 1 hecto-liter (about a barrel) ..hi 

10 hecto-liters =1 kilo-liter k 1 



The square and cubic units are the squares and cubes of 
the linear units. 

The ordinary unit of land area is the Hectare (about 
2^ acres). 



221 



SOAP-MAKING MANUAL 

U. S. BUREAU OF STANDARDS TABLE OF 
METRIC EQUIVALENTS 



Meter = 39.37 inches. 

Legal Equivalent Adopted by Act of Congress July 28, 

1866. 



Length. 

Centimeter = 0.3937 inch 

Meter = 3.28 feet 

Meter = L094 yards 

Kilometer = 0.621 statute mile 

Kilometer = 0.5396 nautical mile 

Inch = 2.540 centimeters 

Foot = 0.305 meter 

Yard = 0.914 meter 

Statute mile = 1.61 kilometers 

Nautical mile = 1.853 kilometers 

Area. 

Sq. centimeter = 0.155 sq. inch 

Sq. meter = 10.76 sq. feet 

Sq. meter = 1.196 sq. yards 

Hectare = 2.47 acres 

Sq. kilometer = 0.386 sq. mile 

Sq. inch = 6.45 sq. centimeters 

Sq. foot = 0.0929 sq. meter 

Sq. yard = 0.836 sq. meter 

Acre = 0.405 hectare 

Sq. mile = 2.59 sq. kilometers 

222 



APPENDIX 

Weight. 

Gram = 15.43 grains 

Gram = 0.772 U. S. apoth. scruple 

Gram = 0.2572 U. S. apoth. dram 

Gram = 0.0353 avoir, ounce 

Gram = 0.03215 troy ounce 

Kilogram = 2.205 avoir, pounds 

Kilogram = 2.679 troy pounds 

Metric ton = 0.984 gross or long ton 

Metric ton = 1.102 short or net tons 

Grain = 0.064 gram 

U. S. apoth. scruple = 1.296 grams 

U. S. apoth. dram = 3.89 grams 

Avoir, ounce = 28.35 grams 

Troy ounce = 31.10 grams 

Avoir, pound = 0.4536 kilogram 

Troy pound = 0.373 kilogram 

Gross or long ton = 1.016 metric tons 

Short or net ton = 0.907 metric ton 

Volume. 

Cu. centimeter = 0.0610 cu. inch 

Cu. meter = 35.3 cu. feet 

Cu. meter = 1.308 cu. yards 

Cu. inch = 16.39 cu. centimeters 

Cu. foot = 0.283 cu. meter 

Cu. yard = 0.765 cu. meter 

223 



SOAP-MAKING MANUAL 



Capaoty. 

Millimeter = 0.0338 

Millimeter = 0.2705 

Liter = 1.057 

Liter = 0.2642 

Liter = 0.908 

Dekaliter = 1.135 

Hectoliter = 2.838 

U. S. liq. ounce = 29.57 

U. S. apoth. dram = 3.70 

U. S. liq. quarts = 0.946 

U. S. dry quarts = 1.101 

U. S. liq. gallon = 3785 

U. S. peck = 0.881 

U. S. bushel = 0.3524 



U. S. liq. ounce 

U. S. apoth. dram 

U. S. liq. quarts 

U. S. liq. gallon 

U. S. dry quart 

U, S. pecks 

U. S. bushels 

millimeters 

millimeters 

liter 

liters 

liters 

dekaliter 

hectoliter 



AVOIRDUPOIS WEIGHT. 

1 pound = 16 ounces = 256 drams 
1 ounce = 16 ** 



TROY (APOTHECARIES') WEIGHT (U. S.) 

1 pound = 12 ounces = 96 drams = 288 scruples = 5,760 grains 

1 ounce = 8 drams := 24 scruples =: 480 grains 

1 dram = 3 scruples = 60 grains 

1 scruple = 20 grains 



WINE (APOTHECARIES) LIQUID MEASURE (U. S.) 



1 gallon = 8 pints 
1 pint 



128 fl. ozs. = 1,024 fl. drams 
16 fl. ozs. =r 128 fl. drams 
1 fl. oz. = 8 fl. drams 
1 fl. dram 



61,440 minims 

7,689 minims 

480 minims 

60 minims 



224 



Useful Infonnatioii 

To find diameter of a circle multiply circumference by 
.31831. 

To And circumference of a circle, multiply diameter by 
3.1416. 

To find area of a circle, multiply square of diameter by 
.7854. 

To find surface of a ball, multiply square of diameter by 
3.1416. 

To find side of an equal square, multiply diameter by 
.8862. 

To find cubic inches in a ball, multiply cube of diameter 
by .5236. 

Doubling the diameter of a pipe, increases its capacity 
four times. 

One cubic foot of anthracite coal weighs about 53 Ib^. 

One cubic foot of bituminous coal weighs from 47 to 50 
pounds. 

A gallon of water (U. S. standard) weighs 8 1/3 pounds 
and contains 231 cubic inches. 

A cubic foot of water contains 7j4 gallons, 1728 cubic 
inches and weighs 62}i pounds. 

To find the number of pounds of water a cylindrical 
tank contains, square the diameter, multiply by .785 and 
then by the height in feet. This gives the number of cubic 
feet which multiplied by 62j^ gives the capacity in pounds 
of water. Divide by 7j4 and this gives the capacity in gal- 
lons. 

A horse-power is equivalent to raising 33,000 pounds 1 
foot per minute, or 550 pounds 1 foot per second. 

225 



SOAP-MAKING MANUAL 

The friction of water in pipes is as the square of velocity. 
The capacity of pipes is as the square of their diameters; 
thus, doubling the diameter of a pipe increases its capacity 
four times. 

To find the diameter of a pump cylinder to move a given 
quantity of water per minute ( 100 feet of piston being the 
standard of speed), divide the number of gallons by 4, 
then extract the square root, and the product will be the 
diameter in inches of the pump cylinder. 

To find the horse-power necessary to elevate water to a 
given height, multiply the weight of the water elevated per 
minute in pounds by the height in feet, and divide the 
product by 33,000 (an allowance should be added for water 
friction, and a further allowance for loss in steam cylinder, 
say from 20 to 30 per cent) . 

To compute the capacity of pumping engines, multiply 
the area of water piston, in inches, by the distance it travels, 
in inches, in a given time. Deduct 3 per cent for slip and 
rod displacement. The product divided by 231 gives the 
number of gallons in time named. 

To find the velocity in feet per minute necessary to dis- 
charge a given volume of water in a given time, multiply 
the number of cubic feet of water by 144 and divide the 
product by the area of the pipe in inches. 

To find the area of a required pipe, the volume and vel- 
ocity of water being given, multiply the number of cubic 
feet of water by 144 and divide the product by the velocity 
in feet per minute. The area being found, the diameter can 
be learned by using any table giving the "area of circles" 
and finding the nearest area, opposite to which will be found 
the diameter to correspond. 

226 



USEFUL INFORMATION 
T Physical and Chemical Oonstants of Fixed Oils and Fats. 

(From Lewkowitsch and other authorities.) 



Linseed oil . 
Hemp-8eed oil 
Wulnat oil . 
Poppy-seed oil 
Sunflower oil 
Fir-seed oil . 
Maize oil . . 
Cotton-seed oil 
Sesame oil . 
Rape-seed oil 
Black mustard oil 
Croton oil . . 
Castor oil . . 
Apricot-kernel oil 
Almond oil . 
Peanut (arachis) oil 
Olive oil . . . 
Menhaden oil 
Cod-liver oil . 
Seal oil ... 
Whale oil . . 
Dolphin oil , 
Porpoise oil , 
Neai;'s-foot oil 
Cotton-seed stearine 
Palm oil . . 
Cacao butter . 
Cocoa-nut oil . 
Myrtle wax . 
Japan wax . . 
Lard .... 
Bone £at . . . 
Tallow . . . 
Butter fat . . 
Oleomarptrine 
Sperm oil . . 
Bottle-nose oil 
Carnauba wax 
Wool-fat . . . 

15^€8WAX • • • 

Spermaceti . . 
Cninesn whx . 
Tung(Chinese wood oil) 
Soya-bean oil 



Speciflc gravity 
atlS<>C. 



0.931-0.938 
0.925-0.931 
0.926-0.926 
0.924-0.927 
0.924-0.926 
0.925-0.928 
0.921-0.926 
0.922-0.930 
0.923-0.924 
0.914-0.917 
0.916-0.920 
0.942-0.955 
0.960-0.966 
0.915-0.919 
0.915-0.920 
0.916-0.920 
0.914-0.917 
0.927-0.933 
0.922-0.927 
0.924-0.929 
0.920-0.930 
0.917-0.918 

0.926 
0.914-0.916 
0.919-0.923 
0.921-0.925 
0.950-0.952 
0.925-0.926 

0.905 
0.970-0.980 
0.931-0.938 
0.914-0.91G 
0.943-0.952 
0.927-0.936 
0.924-0.930 
0.875-0.884 
0.879-0.880 
0.990-0.999 

0.973 
0.958-0.969 

0.960 

0.970 
0.936-0.942 
0.924-0.927 



Speciflc 
gravity 
at 100<>C. 



0.867 
0.856 
0.858 
0.873 
0.875 
0.875 
0.861 

0.860 
0.866 
0.869 
0.833 
0.827 
0.842 
0.901 
0.822 
0.812 
0.810 



Melting-point. 



0.880 


-16«to- 


-26" 


0.871* 


• 


0.873 
0.919 


. *. 4 . 


' .. . 










0.867 




0.871 
0.863 


... . . 


• • 




• 


0.910 




f • 

• • 






0.867 




0.862 








d.874 




0.873 




0.872 




0.871 


. •'.' . 


* • 


0.861 


• ••••• 



SoUdifying-poInt. 



40" 

27»to42* 
30** to 33*» 
20* to 26* 
40* to 44* 

61* to 54.5* 
41* to 46* 
21* to 22* 
42* to 46* 

29.5* to 33* 



84* to 85* 

39* to 42* 

62* to 64* 

43.5* to 49* 

80.5* to 81* 



— 16» 
— 27» 
—27* 
—18* 
—17* 
—27* to —30* 
—10* to —15* 
12* 
— 6* 
-2*10-10' 
—17.5* 
—16* 
—12* to -18* 

—14* 
—10* to —20* 
-3* to —7* 
2* 
—4* 
0* to -10*- 
3* 
—2* 
6*to— 3» 

-16* 

0* to 1.5* 

31* to 32.6* 

25* to' 26* 
16* to 20* 
39* to 43* 

46* 

29* 
15* to 17* 
35* to 37* 
19* to 20* 



-25* 



80* to 81* 
30* to 30.2* 
60.5* to 62* 
43.4* to 44.2* 
80.5* to 81* 
below —17* 

8* to 15* 



227 



SOAP-MAKING MANUAL 







>1~ 


««.■,. 


ssr 


^KT 


mmm 


IM-IH 

'31 
ill 

slili 

an 

■SSSl' 


1 l 

li 

lis 

48° 


"Si" 

IM-UT 

'Ft 

: '. 

10 104 

n i» 

K U> 

1 w 

tI-41 

SA-83 

4.M> 
55-70 


■««■ 

' lis ' 

9*3 

S 
■»:4i.' 


■lit" 

n 

MM 

'oi' 
ok' 


Sisa-".:::; 










■ »-:«i' ■ 




■ «M ■ 





'temperature Correction Table for Hehner's Concen- 
trated Bichromate Solution for Glycerine Analysis 



1 

Tempwture* 


t 

Correeted Volomii 

Ice. 


Logarithm 


11* C 


0.9980 eon 


99918 


120" 


0.9986 *' 


99986 


J30M 


0.9990 " 


VVVMI 


140" 


0.9996 •• 


99978 


150" 


1.0000 " 


00000 


I60" 


i 1.0006 ■' 
1.0010 *' 


00022 


17* •• 


00048 


180" 


1.0016 " 


00066 


19* " 


1.0020 " 


00087 


20* " 


1.0026 " 


00108 


210 " 


1.0080 " 


00180 


229" 


1.0036 " 


00152 


t^r 


1.0040 " 


00178 



'^'Table of Important Fatty Acids ^ 



NanM 


Fonnula 


Mol. 


Boiling Point 


Mdt- 


Nmtnl- 
tetioa 


Wt. 


Ordinaty 
PNanara 


100 gun 
FtaMim 


Butyric 


C4 He Oa 


88 


162.8 


_ 


_ 


687.6 


Caproic.'. . . . 


C«H,aOa 


116 


199.7 


1 


— 


488.6 


Capm}ic,.«. 


CaHieQa 


144 


286—237 


^■■^ 


16.6 


889.6 


Capric....... 


Cio H20 O2 


172 


268—270 


199.6—200 


81.8 


826.2 


Laurie: .'«.i. 


C|2 U24 O2 


200 


— 


226 


48.6 


280.5 


Myristic. ... 


Ci-4 H2e O2. 


228 


— 


260.6 


58.8 


246.1 


Palmitic.. «. 


Cie H32 O2 


266 


— 


268.5 


62 


219.1 


Stearic 


Cie Hae O2 


284 ' 


— . 


291 


69.2 


197.5 


Arachidic... 


C2oH4o0a 


802 


— 


-.- 


76 


186.8 


Behenic j 


C22 H44 O2 


830 


,— 


— 


77-78 


170.0 


OerotiCft.. 
MeU«uc..:...' 


C27H94O2 


400 


— 


— 


78 


140.25 


C3oH;o02 


442 


-=- 


— 


90 


126.6 


Oleic,,.,... 


•CiaH34 02 


282 


— 


185.5—286 


14^ 


198.9 


Sriidc^^;. 


^zz H42 O4 


388 


— 


— 


88-34 


i6&.9 


Linolic...... 


C,eH,2 02 


280 


-^ 


t 


— 


200.4 


Linolenic*. . . 


Cie Hao O2 


278 




— 


— 


201.S 


Ridnoleic. . .' 


Gi8H34 0s 


298 


— 


— 


— 


181.6 



«1<1A 



SOAP-MAKING MANUAL 



^Comparison of Thermometer Scdes 



n DegrM Cdri|iV3=|ii PegrM Reaumiir==82+-|ii Degree Fahrenhdt 
n Degree lte«ttisiir»|ii Degree Cid8iii8=82-{-|'n Degree Fahrenheit 
n Degr#d Fthrenheit=-|*(ii-*B2) Degree Cebiue=:-|-(n— ^) J>eg. R 



c 


R. 


t; 


c. 


R. 1 P. 


a 


R, 


F. 


a 


R. 


P. 


— ao 


—16 


—I 


to. 


16 


68 


60 


48 


140 


100 80 


^12 


-^i» 


— 1S.8 


-8.2 


21 


16.8 


69.8 


61 


SS 


141.8 


101 80.8 


218.8 


—18 


—14.4 


-0.4 


22 


17.6 


71.6 


62 


148.6 


102 


81.6 


216.6 


—17 


—18.6 


1.4 


28 


18.4 


78.4 


68 


60.4 


146.4 


108 


82.4 } 217.4 


—16 


-18.8 


8.8 


24 


19.8 


76.2 


64 


61,2 


147.8 


104 


88.2 : 219.2 

1 


—15 


—IS 


6 


26 


20 


77 


66 


62 


149 


106 


84 f 221 


—14 


— M.« 


6.8 


26 


20.8 


78.8 


66 


62.8 


160.8 


106 


84.8 222.8 


—18 


*-10.4 


iS:l 


27 


21.6 


80.6 


67 


68.6 


168.6 


107 


86.6 824.6 


—18 


-ii 


28 


22.4 


82.4 


68 


64.4 


164.4 


108 


86.4 226.4 


—11 


U.S 


29 


28.2 


84.2 


69 


66.2 


166.8 


109 


87.8 


2282 


—10 


—•8 


u 


80 


24 


86 


70 


66 


1S8. 


110 


88 


tto 


— • 


—^.8 


16.8 


81 


24.8 


87.8 


71 


66.8 


169^ 


lit 


88.8 


281.8 


— 8 


r^6.4 


17.6 


82 


86.6 


89.6 


72 


87.6 


161.6 


112 


89.6 


888.6 


•^T 


.^fli.6 


18.4 


88 


26.4 


91.4 


78 


68.4 


168.4 


118 


90.4 


886.4 


— • 


-..4.8 


21.2 


84 


27.2 


98.2 

1 


74 


60.2 


166.2 


114 


91.2 


287.2 


— 6 


^ 4 . 


28 


86 


28 


8f 


76 


60 


167 


116 


92 


889 


— 4 


— S.8 


24.8 


86 


28.6 


96.8 


76 . 


60.8 


168.8 


116 


92.6 


240.8 


— 8 


r— 2.4 


26.6 


87 


29.6 


98.6 


77 


61 .« 


170.6 


117 


98.6 


242.6 


— B 


— 1.6 


28.4 


88 


80.4 


100.4 


78 


68.4 


172.4 


118 


94.4 


244.4 


— I 


— 0.8 


80.8 


89 


81.8 


102.2 


79 


.68.8 


m.8 


119 


95.2 


246.2 








*88 


40 


88 


104 


80 


64 


176 


120 


96 


248 


1 


0.8 


88.8 


41 


88.8 


106.8 


81 . 


64.8 


177.8 


121 


96.8 


249.8 


8 


1.6 


86.6 


48 


88.6 


107.6 


88 


66.6 


179.6 


128 


97.6 


862.6 


8 


2.4 


87.4 


48 


84.4 


100.4 


88 


66.4 


181.4 


128 


98.4 


258.4 


4 


8.2 


89.2 


44 


86.2 


111.2 


84 


67.1 


188.8 


124 


99.2 


256^2 


S 


4 


41 


46 


86 


118 


86 


68 


iiss 


126 


^tt. 


267 


? 


4.8 


42.8 


46 


86.8 


114.8 


86 


68.8 


m 


m 


100.8 


IS! 


6.6 


44.6 


47 


87.6 


116.6 


87 


70'.4 


t27 


101.6 


260.6 


8 


6.4 


46.4 


48 


88.4 


118.4 


88 


190.4 


128 


108.4 


262.4 


• 


7.2 


48.2 


49 


89.8 


120.1 


88 


n.t 


182.2 


129 


108.8 


264.2 


10 


8 


60 


60 


40 


122 


90 


72 


IN 


180 


104 


286 


11 


8.8 


61.8 


61 


40.8 


128.8 


91 


78.8 


198.8 


181 


104.8 


867.8 


18 


8.6 


68.6 


62 


41.6 


186.6 


98 


78.6 


197.6 


182 


185.6 


288.6 


IS 


10.4 


66.4 


68 


42.4 


127.4 


98 


74.4 


199.4 


188 


106.4 


271.4 


14 


11.2 


67.2 

I, 


64 


48.2 


129.2 


94 


76.2 


tOl.2 


184 


107^8 


278.2 


IS 


12 


69 


66 


44 


181 


96 


7$ 


208 


186 


108 


875 


16 


18.8 


60.8 


66 


44.8 


188.8 


96 


76.8 


204.8 


186 


108.8 


876.8 


17 


18.6 


62.6 


67 


46.6 


184.6 


97 


77.6 


206.6 


187 


109.6 


878.6 


IS 


14.4 


64.4 


68 


46.4 


186. 4 


98 


78.4 


208.4 


188 


110.4 


880.4 


19 


16.8 


66.2 


00 


47.S 


188.8 

-k— ^ 


99 


79.8 


210.2 


189 


111.2 1 288.8 

1 



230 



USEFUL INFORMATION 



^Quantities of Alkali Required for Saponification of 
Fats of Average Molecular Weight 670 

(Cocoanut Oil, Palmkemel Oil) 



I 



Knoa 



1000 
1000 



4000 
6000 
OOOO 

7000 
8000 
9000 

10000 



litenAIkaU 

Solutioo 

Spb Gr. 1.1 



NaOH 



1876.88 

8761.ee 

6827.60 

7608.88 

9879.16 

11264:99 

18180.82 

16006.66 

18888.49 

18768.88 



KOH 



1902.99 

3805.97 

6708.96 

7611.94 

9614.96 

11417.91 

18820.90 

16228.88 

17126.87 

19029.86 



litenAIkaU 

Sdution 
Sp. Gr. IJi 



Na OH I K O H 



844.67; 
1688.86 
8684.02 
8878.691 
4228.87 
6068.04 
6912.71 



litenAIkaU 

Solution 
Sp. Gr. 1.8 



UteraAlkaU 

Solttti(m 
Sp. Gr. 1.856 



Na OH 



KOH ! Na OH 



8767.88 
7602.06 
8446.78 



980.86 
1860.70 
2791.04 
8721.89 
4651.74 
6582.09 
6512.44 
7442.78 
8878.18 
9808.48 



610.27 
1020.64; 
1680.81. 
2041.011 
2561. 85i 
8061.61 
8571.88; 
4082.15 
4692.42 
6102.69 



622.71] 
1245.41 
1868.12: 
2490.83; 
8113.54 
8786.24; 
4358.95 
4981.66 
6604.36 
8227.02 



409.61 
819.21 
1228.82 
1688.43 
2048.04 
2457.66 
2867.26 
8276.86 
8886.47 
4096.08 



KOH 



517.97 
1035.95 
1653.92 
2071.90 
2589.87 
3107.84 
8625.82 
4143.79 
4661.77 
6179.74 



'I'Ouantities of Alkali Required for Saponification of 
Fats of Average Molecular Weight 860 

(Tallow, Cottonseed Oil, OUve Oil, Etc.) 



VfLi« 


LitmAlkaH 

Sohition 
Sp. Gr. 1.1 




NaOH 


KOH 


1000 


1461;40 


1482.66 


2000 


2922.81 


2965.12 


8000 


4884.21 


4447.87 


4000 


6846.62 


5930.23 


6000 


7807.02 


7412.79 


60C0 


8768.42 


8895.86 


7000 


10229.83 


10377.91 


8000 


11691.28 


11860.46 


9000 


18168.64 


18848.02 


10000 


14614.04 


14826.58 



litwa Alkali 

Solution 
Sp. Or. 1.2 



Na OH 



KOH 



668.06; 
1816.12; 
1974.18 
*2682.24 
8290.80 
8948.85 
4606.41 
6264,47 
6922.68 

6680.69! 

I 



724.81 
1449.61 
2174.42 
2899.22 
8624.03 
4348.84 
6078.64 
6798.45 
6628.26 
7248.06 



Uten Alkali 

SohatioB 
Sp. Or. 1.8 



Na OH KOH 



897.54 
796.07| 
1192.61; 
1590. 14i 
1987.68! 
2386.21| 
2782.75 
3180.28: 
8577.82- 
8976.35! 



485.13 
970.27 
1455.40 
1940. 53| 
2425,67' 
2910.80| 
8395.931 
8881.06 
4366.20 
4861.33 



litenAIkaU 

Solution 
Sp. Gr. 1.355 



Na OH 



KOH 



319.11 

638.23 

957.341 

1276.45! 

1595. 67j 

1914.68, 



2233.79; 
2552.90, 
2872.02' 
8191.13' 



403.54 
807.08 
1210.61 
1614.15 
2017.69 
2421.23 
2824.77 
8228.30 
8631.84 
4636.38 



231 



SOAP-MAKING MANUAL 

DENSITY AND STRENGTH OF SULPHURI 

ACID (SIDERSKY). 



1 







£<)uivaleiit 
(m^cc) 


1 


O 




Equivalem 
(in cc.) 


•o 


o 


H 


t — - — / 


L. 


•o 


o 


u 




A^. . 


ft 


*n 


« . 


r 


» 


i 


u« 


«• . 






g 


V4 


x^ 






v4 


x^ 






f 




g<5 






f 


tS 


a 




o 


I 






|1 




1 










s_ 


Q. 

1.007 


1.9 


o a 
52.620 


OB. 
96.930 


Q 




^ 


o a 


«4M 

o 


1 


62 


1.308 


40.2 


1.905 


3.50 


3 


1.014 


2.8 


35.710 


66.450 


64 


1.320 


41.6 


1.821 


3.35 


4 


1.022 


3.8 


25.650 


47.230 


66 


1.332 


43.0 


1.745 


3.21 


6 


1.029 


4.8 


20.410 


37.582 


69 


1.345 


44.4 


1.665 


3.08 


8 


1.037 


5.8 


16.670 


30.690 


71 


1.357 


45.5 


1.621 


2.98 


9 


1.045 


6.8 


14.085 


25.938 


74 


1.370 


46.9 


1.558 


2.86 


10 


1.0S2 


7.8 


12.198 


22.460 


77 


1.383 


48.3 


1.497 


2.75 


12 


1.062 


8.8 


10.755 


19.803 


80 


1.397 


49.8 


1.436 


2.64 


13 


1.067 


9.8 


9.524 


17.540 


82 


1.410 


51.2 


1.386 


2.55 


15 


1.075 


10.9 


8.547 


15.740 


85 


1.424 


52.6 


1.335 


2.45 


17 


1.083 


11.9 


7.752 


14.278 


88 


1.438 


54.0 


1.287 


2.37 


18 


1.091 


13.0 


7.042 


12.969 


91 


1.453 


55.4 


1.237 


2.27 


20 


1.100 


14.1 


6.452 


11.882 


94 


1.468 


56.9 


1.195 


2.20 


22 


1.108 


15.2 


5.953 


10.962 


97 


1.483 


58.3 


1.156 


2.13 


23 


1.116 


16.2 


5.526 


10.177 


100 


1.498 


59.6 


1.U6 


2.05 


25 


1.125 


17.3 


5.405 


9.954 


103 


1.514 


61.0 


. 1.080 


1.98 


27 


1.134 


18.5 


4.76 


8.770 


106 


1.530 


62.5 


1.045 


1.93- 


29 


1.142 


19.6 


4.465 


8.223 


108 


1.540 


64.0 


1.010 


1.86 


30 


1.152 


20.8 


4.184 


7.723 


113 


1.563 


65.5 


0.975 


1.80 


32 


1.162 


22.2 


3.876 


7.138 


116 


1.580 


67.0 


0.950 


1.74' 


34 


1.171 


23.3 


3.663 


6.745 


120 


1.597 


68.6 


0.917 


1.691 


36 


1.180 


24.5 


3.541 


6.521 


123 


1.615 


70.0 


0.888 


1.631 


38 


1.190 


25.8 


3.258 


5.999 


127 


1.634 


71.6 


0.855 


1.571 


40 


1.200 


27.1 


3.077 


5.666 


130 


1.652 


73.2 


0.845 


1.521 


42 


1.210 


28.4 


2.907 


5.353 


134 


1.671 


74.7 


0.800 


1.47< 


44 


1.220 


29.6 


2.770 


5.102 


138 


1.691 


76.4 


0.774 


1.431 


46 


1.231 


31.0 


2.618 


4.865 


142 


1.711 


78.1 


0.749 


1.39( 


48 


1.241 


32.2 


2.500 


4.604 


146 


1.732 


79.9 


0.722 


1.321 


50 


1.252 


33.4 


2.392 


4.406 


151 


1.753 


81.7 


0.705 


1.281 


53 


1.263 


34.7 


2.283 


4.205 


155 


1.774 


84.1 


0.672 


1.23) 


55 


1.274 


36.0 


2.179 


4.012 


160 


1.798. 


86.5 


0.639 


1.19( 


57 


1.285 


37.4 


2.079 


3.829 


164 


1.819 


89.7 


0.609 


l.UI 


60 


1.297 


38.8 


1.988 


3.661 


168 


1.842 


100.0 


0.544 


1.00( 



232 



mnkat 
[met) 



ti 
w 

3.508 
3.354 

3.214 

3.085 

2.985 

2M9 

2.7SJ 

2.646 

2.SS1 

2.459 

2J70 

2.27C 

2.200 

2.130 

2.050 

1.980 

1.930 

1.860 

1.800 

1.740 

1.690 

1.630 

1.570 ■ 

1.520 

1.470 

1.430 

1.390 

1.320 

1.280 

1.235 

1.190 

1.130 

1.000 



USEFUL INFORMATION 

^Densities of Potassium Carbonate Solutions 

at 15 C (Gerlacfa) 



>HURIC — 



Sp. Gr. 



1.00914 
1.01829 
1.02748 
1.03668 
1.04672 
1.06618 
1.06464 
1.07896 
1.08837 
1.09278 
1.10268 
1.11288 
1.12219 
1.18199 
1.14179 
1.16200 
1.16222 
1.17248 



Percent 
of pure 
KzCOs 



1 

2 

8 

4 

6 

6 

7 

8 

9 

10 

II 

12 

18 

14 

16 

16 

17 

18 



Sp. Gr. 



1.18266 
1.19286 
1.20344 
1.21402 
1.22469 
1.28617 
1.24675 
1.26681 
1.26787 
1.27898 
1.28999 
1.80106 
1.81261 
1.32417 
1.33678 
1.84729 
1.86886 
1.37082 



Percent 
of pure 
KzCOa 



19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
80 
31 
82 
88 
84 
86 
36 



Sp. Gt, 



Percent 
of pure 
K2CO3 



1.88279 
1.39476 
1.40673 
1.41870 
1.43104 
1.44338 
1.45673 
1.46807 
1.48041 
1.49814 
1.60688 
1.61861 
1.58136 
1.64408 
1.S6728 
1.57048 
1.67079 



\ 



87 
38 
89 
40 
41 
42 
48 
44 
45 
46 
47 
48 
49 
50 
61 
62 
68.024 



=c 



♦Constants of Certain Fatty Acids and Triglycerides 



Tri^yoerldefr 
of 


Mol.Wt. 

ofFattgr 

Add 


Mol. Wt. 

ofTri- 

slyceridea 


Per cent Yieid' 


FMty 
Add 


GlymUm 


Stearic Add 


284 
282 
270 
266 
228 
200 
172 
116 
88 


890 
884 
848 
806 
722 
638 
694 
886 
802 


1 1 

96.78 
96.70 
96.62 
95.28 
94.47 
94.04 
98.14 
90 16 


16^ 
14,41 
10.85 
11.42 

12 74 


Oleic Add 


liargaric Add 


PftlmiticAdd.......... 

MyriitieAdd 


Laurie Add . ^ 


14.42 
15.48 


Capric Add 


Caproie Add 


Butyric Add « . . 


87.41 AA Ait 









2.1.1 



SOAP-MAKING MANUAL 



PERCENTAGES OF SOLID CAUSTIC SODA AND CAUSTIC 
POTASH IN CAUSTIC LYES ACCORDING TO BAUME SCALE. 



Degrees 


% 


% 




Degrees 


% 


% 


Baume. 


NaOH 


KOH 




Baume. 


NaOH 


KOH 


1 


0.61 
0.93 
2.00 


0.90 
1.70 
2.60 




26.. 
27.. 
28.. 




... 19.58 
... 20.59 
... 21.42 


24.20 


2 


25.10 


3 


26.10 


4 


2.71 


3.50 




29.. 




... 22.64 


27,00 


5 


3.35 


4.50 




30.. 




... 23.67 


28.00 


6 


4.00 


5.60 




31.. 




... 24.81 


28.90 


7 


4.556 
5.29 


6.286 
7.40 




32.. 
33.. 




... 25.80 
... 26.83 


29.80 


8 


30.70 


9 


5.87 


8.20 




34.. 




... 27.80 


31.80 


10 


6.55 


9.20 




35.. 




... 28.83 


32.70 


11 


7.31 


10.10 




36.. 




. . . 29.93 


33.70 


12 


8.00 


10.90 




37.. 




... 31.22 


34.90 


13 


8,68 


12.00 




38.. 




... 32.47 


35.90 


14 


9.42 


12.90 




39.. 




... 33.69 


36.90 


IS 


10.06 


13.80 




40.. 




... 34.96 


37.80 


16 


10.97 


14.80 




41.. 




... 36.25 


38.90 


17 


11.84 


15.70 




42.. 




... 37.53 


39.90 


18 


12.64 


16.50 




43.. 




... 38.80 


40.90 


19 


13.55 


17.60 




44.. 




... 39.99 


42.10 


20 


14.37 


18.60 




45.. 




... 41.41 


43.40 


21 


15.13 


19.50 




46.. 




... 42.83 


44.60 


22 


15.91 


20.50 




47.. 




... 44.38 


45.80 


23 


16.77 
17.67 


21.40 
22.50 




48.. 
49.. 




... 46.15 


47.10 


24 




... 47.58 


48.25 


25 


18.58 


23.30 




50.. 




... 49.02 


49.40 


GLYCERINE CONTENT OF 


MORE 


COMMON OILS AND 




FATS 


USED 


IN 


SOAP 


MAKING. 




• 

a 
i4 


Theoretical 
Yield of Pure 
Glycerine of 
Neutral Oil 
or Fat. 


u 

u 

> 


ratty Acia in 

Commercial 

Oil. 


% Pure Gly- 
cerine in Com- 


mercial Oil. 
Yield Soap Lye 


• c 

V 

> u 


Beef Tallow. .. 




10.7 
10.5 


1 
2< 




1—50 


10.2 
5.2- 


12.75 
- 8.4 6.5 - 




Bone Grease . . 




-10.5 


Castor Oil 




9.8 


0.: 


5—10 


8.8- 


- 9.8 11.0 - 


-12.45 


Cocoanut Oil. 




13.9 


« 


J— 5 


13.2- 


-13.5 16.5 - 


-16.9 


Cocoanut Oil Off. . . . 


• • • • 


i; 


)— 40 


8.3- 


-11.8 10.37- 


-14.75 


Corn Oil 




10.4 


] 


I— 10 


9.3- 


-10.3 11.62- 


-12.9 


Cottonseed Oil 




10.6 


1 


Prace 


10.6 


13.25 




IIos Grease. . . 




10.6 
10.6 


0.. 

] 


5—1 

1—3 


10.5- 
10.5- 


-10.6 13.12 
-10.6 13.12 


-13.25 


Horse Grease. 




-13.25 


Olive Oil 




10.3 


i 


2—25 


7.7- 


-10.2 9.62 


-12.75 


Olive Foots... 




• • • • 


3( 


3—60 


4- 


-7 5 


- 8.75 


Palm Oil 




11.0 


1( 


3—50 


5.5- 


-10 6.87 


-12.5 


Palmkernel Oil 


13.3 


t 


4—8 


12.2- 


-12.8 15.25—16 


Peanut Oil . . . 




10.4 




5—20 


8.3- 


- 9.9 10.37 


-12.37 


Soy^ Bean Oi 


1 


10.4 




2 


10.2 


12.75 




Train Oil 




10.0 
10.9 




2—20 
1—3 


8— 9.8 10.0 • 
10.5—10.8 13.12 


-12.25 


VegetSable Tallow. . . . 


-13,5 



234 



USEFUL INFORMATION 



Ai\D cm 

% K 


♦Table <rf Specific Gravities of Pure 


i Con 


unercial 


Glycerine with Corresponding Percentage of 


XaOH KOI 




W ater. Temperature 1 5 C. 




19.58 2<J 












20.59 2111 
21.42 2i'i 


Sp. Gr. 




Sp. Gr. 






22.64 M 


1.262 


Water 


1.160 


88% 


Water 


'3.67 M 
W M 
5.80 25.1 


1.261 


1% " • 


1.167 


89" 


»• 


1.258 


2" 


1.166 


40" 


•» 


S.83 m 


1.266 


8" 


1.162 


41" 


tt 


'M 31M 


1.2615 


40 M 


1.149 


42" 


•t 


.83 31H 
93 ilH 


1.260 


6" 


1.1464 


48" 


t* 


'n K« 


1.2467 


6" 


1.1487 


44" 


*t 


47 35.5(1 


1.2460 


7" 


1.141 


46" 


9t 


59 36.50 


1.24S 


8" 


1.1377 


46" 


ti 


'5 3«.50 


1.241 


9" 


1.1863 


47" 


tf 


J m 


1.287 


10 " 


1.1326 


48" 


n 


3 40.90 
? 42.10 


1.286 


11 " 


1.1804 


49" 


•• 


1.2324 


12 " 


1.127 


60" 


»t 


44.60 


1.229 


18 " 


1.126 


61" 


f» 


45.80 
47.10 
48.25 


1.2265 


14 " 


1.1224 


62" 


ft 


1.2245 


16 " " 


1.1204 


68- 


tf 


49.40 


1.2225 


16 " " 


1.117 


64" 


»• 


m 


1.2186 


17 " " 


1.114 


66" 


t$ 




1.2174 


18 " " 


1.112 


66" 


»» 


t 


1.2142 


19 " " 


1.109 


67" 


»* 


^. 


1.211 


20 " 


1.106 


58" 


t* 


u G 


1.207 


21 " 


1.108 


69" 


t* 


V 


1.208 


22" 


1.1006 


60" 


tt 


> o 


1.2004 


23 " 


1.088 


66" 


*t 





1.198 


24 »• 


1.076 


70" 


t* 


-10.5 
-12.45 


1.196 


26 " 


1.0623 


76" 


t» 


1.1928 


26 " 


1.049 


80" 


t> 


■16.9 


1.189 


27 " 


1.0365 


85" 


•» 


UJS 


1.188 


28 •' 


1.0243 


90" 


t* 


12.9 

1 


1.1846 


29 " 


1.0218 


91" 


i» 


15.25 1 


1.182 


80 " 


1.0192 


92" 


f> 


15.25 f 


1.179 


81 '• 


1.0168 


93" 


»t 


2,75 
S.7S 

2.S 


1.176 


82 " 


1.0147 


94" 


*9 


1.1784 


88 " 


1.0126 


95" 


•» 


5 


M71 


84" 


1.01 


96" 


»• 


1.57 


1.168 


^6 " 


1.0074 


97" 


tt 


25 


1.166 


86" 


1.0053 


98" 


tt 


^ 1 
t 


1.168 


87 " " 


1.0026 


99" 


•0 



I 



235 



SOAP-MAKING MANUAL 



n'able of Peicentaget Specific GimTitj and Beaume 
Degree of Pure Gtycerine Sohitioiie 



Ptremt 
Watvr 


Sp.Or. 
Chftmirfoii 


Dcgne 
Beaiime 


Water 


^.Gr. 

Chimpkm 


DegTM 
BaaoiiM 


and PtUtt 


(Qerthdot) 


andPdtet 


(BirUMlot) 





1.2640 


81.2 


u.a 


1.2860 


28.6 


0.6 


1.2626 


81.0 


11.6 


1.28^ 


28.4 


1.0 


1.2612 


80.9 


12.0 


1.2822 


28.8 


1.6 


1.2600 


80.8 


12.6 


1.2807 


28.2 


2.0 


1.2686 


80.7 


18.0 


1.2296 


28.0 


2.6 


1.2676 


80.6 


18.6 


1.2280 


27.8 


8.0 


1.2660 


80.4 


14.0 


1.2270 


27.7 


8.6 


1.2646 


80.8 


14.6 


1.2266 


27.8 


4.0 


1.2682 


80.2 


16.0 


1.2242 


27.4 


4.6 


1.2620 


80.1 


16.6 


1.2280 


27.8 


6.0 


1.2606 


80.0 


16.0 


1.2217 


27.2 


6.6 


1.2490 


29.9 


16.6 


1.2202. 


27.0 


6.0 


1.2480 


29.8 


17.0 


1.2190 


28.9 


6.6 


1.2466 


29.7 


17.6 


1.2177 


26.8 


f.O 


1.2466 


29.6 


18.0 


1.2166 


26.7 


T.6 


1.2440 


29.6 


18.6 


1.2160 


26.6 


8.0 


1.2427 


29.8 


19.0 


1.2187 


26.4 


8.6 


1.2412 


29.2 


19.6 


1.2126 


26.8 


9.0 


1.2400 


29.0 


20.0 


1.2112 


26.2 


9.6 


1.2890 


28.9 


20.6 


1.2100 


26.0 


10.0 


1.2876 


28.8 


21.0 


1.2086 


26.0 


10.6' 


1.2862 ; 


' 28.7 









236 



USEFUL INFORMATION 



1 



tioos with 



Pure Glycerinci Solu< 
Beaume Degree 



and Percent Water 



Percent 
Water 


Sp. 6r. 


Degree 
Beaiime 


Percent : 
Water , 


Sp. Gr. 


Degree 
Beaume 


0.0 


1.2640 


81.2 


1.0 ' 


1.2612 


80.9 


0.6 


1.2626 


81.0 


1.5 ' 


1.2600 


80.8 


2.0 


1.2686 


80.7 


12.0 


> 1.2322 


28.8 


2.6 


1.2676 


80.6 


12.5 


1.2807 


28.2 


8.0 


1.2560 


i 80.4 


18,0 


1.2296 


28.0 


8.6 


1.2646 


80.8 


18.6 ; 


1.2280 


27.8 


4.0 


1.2682 


80.2 


14.0 


1.2270 


27.7 


4.6 


1.2520 


80.1 


14.6 


1.2256 


27.6 


6.0 


1.2506 


80.0 


1^.0 


1.2242 


27.4 


6.6 


1.2490 


29.9 


15.5 


1.2280 


27.8 


6.0 


1.2480 


29.8 


16.0 


1.221T 


27.2 


6.6 


1.2466* 


29.7 


16.6 


1.2202 


27.0 


7.0 


1.2466 


29.6 


17.0 


1.2190 


26.9 


7.6 


. 1.2440 . 


, 29.6 


17.6 


1.2177 


26.8 


S.O i 


1.2427 1 


29.8 


18.0 


1.2166 


26.7 


8.6 


1.2412 


29.2 


18.6 


1.2160 


26.6 


9.0 


1.^400 


29.0 


19.0 


1.2187 


26.4 


9.6 


1.2890 


28.9 


19.6 


1.2126 


26.8 


10.0 


1.2876 


28.8 


20.0 


1.2112 


26.2 


10.6 


1.2868 


28.7 


20.6 


1.2100 


26.0 


11.0 


1.2800 


28.6 


21.0 


1.2086 


26.9 


11.6 


.1.2886 


28.4. 


r 


• 

1 




J 


« 


=ss=s= 







237 



'4 



INDEX 



Acetin process for the deter- 
mination of glycerol, 155. 

Acid, Clupanodonic, 20. 

Acid, Hydrochloric, 111. 

Acid, Laurie, 2. 

Acid, Myristic, 2. 

Acid, Napthenic, 24. 

Acid, Oleic, 15, 19. 

Acid, Palmitic, 2. 

Acid, Pinic, 22. 

Acid, Resin, 144. 

Acid, Stearic, IS, 19. 

Acid, Sulfuric, 112. 

Acid, Sylvic, 22. 

Acid saponification, 120. 

Air bleaching of palm oil, 12. 

Albuminous matter. Removal 
from tallow, 6. 

Alcohol, Denatured, 82. 

Alcoholic method for free alkali 
in soap, 139. 

Alkali Blue 6 B, indicator, 129. 

Alkali, Total, determination of in 
soap, 147. 

Alkalis, 25. 

Alkalis used in soap making, 
Testing of, 134. 

Amalgamator, 33. 

Analysis, Glycerine, Interna- 
tional, 150. 

Analysis, Soap, 137. 

Analysis, Standard methods for 
fats and oils, 165-196. 

Aqueous saponification, 121. 

Arachis oil, 79. 

Autoclave saponification, 118. 

Automobile soaps, 41. 

B 

Barrels, sampling, 168. 

Baume scale, 25. 

Bayberry wax. Use in shaving 
soap, 89. 

Bichromate Process for glycerol 
determination, 160. 

Bleachine, Fullers' earth process 
for tallow, 4. 

Bleaching palm oil by bichro- 
mate method, 9. 



Bleaching palm oil by air, 12. 

Bosshard & Hug^enberg method 
for determination of free al- 
kali, 140. 

Bunching of soap, 52. 

C 

Candelite, 96. 

Candle tar, 125. 

Carbolic soap, 77. 

Carbon Dioxide, Formation of in 

carbonate saponification, 45. 
Caibonate, potassium, 29. 
Carbonate, saponification, 35, 45. 
Carbonate, sodium, 28. 
Castile soap, 79. 
Castor oil ferment, 121. 
Castor oil, Use of in transparent^ 

soaps, 83. 
Caustic potash, 26. 
Caustic potash. Electrolytic, 27. 
Caustic soda, 26. 
Changes in soap-making, 36. 
Chemist, Importance of, 127. 
Chipper, Soap, 32. 
Chip soap, 54. 

Chip soap. Cold made, 55. 
Chip soap. Unfilled, 56. 
Chrome bleaching of palm oil. 9. 
Cloud test for oil. Standard 

method, 182-183. 
Clupanodonic acid, 20. 
Cocoanut oil, 6. 
Cold cream soap, 78. 
Cold made chip soaps, 55. 
Cold made toilet soaps, 72. 
Cold made transparent soaps, 84. 
Cold process, 35, 43. 
Colophony, 22. 
Coloring soap, 75. 
Copra, 7. 
Corn oil, 14. 
Corrosive sublimate, 78. 
Cotton goods. Soaps used for, 

103. 
Cottonseed oil, 14. 
Cream, Shaving, 90. 
Crude glycerine, 113. 
Crutcher, 32. 
Curd soap, 71. 
Cutting table, 32. 



239 



SOAP-MAKING MANUAL 



D 

Determination of free fatty acid, 

128. . 
Determination of unsaponifiable 

matter, 132. 
Distillation of fatty acids, 125. 
Drying machine, 32. 

E 

Enzymes, 17. 
Eschweger soap, 81. 
Examination of fats and oils, 
128. 

F 

Fahrion's method for moisture, 
138. 

Fats and oils, Examination of, 
128. 

Fats and oils used in soap manu- 
facture, 3. 

Fattv acids 14 

Fatty acids,* Distillation of, 125. 

Ferments, Splitting fats with, 
121. 

Fillers for laundry soaps, 53. 

Fillers for soap powders, 58. 

Finishing change, 36. 

Fish oils, 20. 

Floating soap, 62. 

Formaldehyde soap, 78. 

Frames, 31. 

Free alkali in soap, Determina- 
tion of, 139. 

Free fatty acid, Determination 
of, 128. 

Free fatty acids. Extraction from 
tallow, 6. 

Free fatty acid, Standard method 
of dilu., 174 Note on method, 
188-189. 

Full boiled soaps, 35. 

Fullers* earth bleaching of tal- 
low, 4. 

G 

Glycerides, 2, 

Glycerine, 2. 

Glycerine analysis, 150. 

Glycerine change, 36. 

Glycerine, Crude, 113. 

Glycerine in spent lyes. Recov- 
ery of, 106. 

Glycerine in soap. Determination 
of, 149. 

Glycerine, Sampling crude, 162. 



Glycerine soaps, 83. 

Glycerol content. Ways of cal- 
culating actual, 159. 

Glycerol determination, Acetin 
process, 155. 

Glycerol determination. Bichro- 
mate process for, 160. 

Graining soap, 30. 

Grease, 21. 

Grease, Bleaching, 21. 

Grinding soap, 34. 

H 

Hand Paste, 93. 

Hard water, 29. 

Hardened oils in toilet soap. Use 

of, 96. 
Hydrocarbon oils, 2. 
Hydrogenating oils, 19. 
Hydrolysis of fats and oils, 17. 
Hydrolytic dissociation of soap, 

1. 
Hydrometers, 25. 



Indicators, Action, 135-6. 

Insolul}le impurities in fatty oils, 
Determination of (standard 
method) 172. Note on method 
187. 

Insoluble matter in soap, deter- 
mination of, 143. 

International committee on gly- 
cerine analysis, 150. 

Iodine manufacturing oil, 191. 

Iodine member Wijs method. 
Standard, 177-181. Note on 
method, 191. 

Iodine soap, 78. 



Joslin, ref., 113. 

K 

"Killing*' change, 36. 
Koettstorfer number (Standard 

method), 181-182. 
Kontakt reagent, 117. 
Krebitz Process, 123. 
Krutolin, 96. 

L 

Leiste & Stiepel method for 

rosin in soap, 146. 
Liebermann, Storch reaction, 

144. 



240 



INDEX 



Light powders, 60. 

Laundry soap, 48. 

LeBlanc Process, 28. 

Lewkowitsch, rex., 17, 146. 

Lime Saponincation, 118. 

Lime, Use in Krebits Process, 
123. 

Lime, Use in treatment of gly- 
cerine water, 116. 

Liquid medicinal soaps, 79. 

Liquid soaps, 94. 

Lyes, Spent, 37. 

M 

Magnesia, Use in autoclave 

saponification, 120. 
Manganese sulfate. Use of as 

catalyzer in fermentative cleav- 
age of fats, 122. 
Marine soaps, 39. 
Medicinal soaps, 76. 
Medicinal soaps, Less important, 

78. 
Medicinal soaps, Therapeutic 

value of, 76. 
Melting point of fat or oil. 

Standard method, 193. 
Mercury soaps, 78. 
Metallic soaps, 1. 
Methyl orange, indicator, 136. 
Meyerheim, ref., 21. 
Mill soap. 32. 
Moisture in soap, Determination 

of, 138, 130. 
Moisture and volatile matter in 

fats and oils, Standard 

method for detm. of, 170. Note 

on method, 184-185. 
Mottle in soap, 81. 
Mug shaving soap, 90. 

N 

Naphtha, Incorporation in soap, 

49. 
Naphthenic acids, 24. 
Nigre, 36. 
Normal acids. Equivalent in al< 

kalis, 136. 



Oils and fats, 1. 
Oils and fats, Chemical con- 
stants, 18. 
Oils and fats. Distinction, 1. 
Oils and fats, Preserving, 18. 



Oils and fat. Nature of used in 

soap manufacture, 2. 
Oils and fats, Rancidity of, 16. 
Oil hardening, 19. 
Oleic acid, 15, 19. 
Olein, 2, 19. 
Olive oil, 14. 
Olive oil foots, 14. 
Organoleptic methods, 127. 



Palmatin, 2. 

Palm kernel oil, 8. 

Palmitic acid, 2. 

Palm oil, 8. 

Palm oil, air bleaching, 12. 

Palm oil. Chrome bleaching of, 
9. 

Palm oil soap, 66. 

Pearl ash, 29. 

Perfuming and coloring toilet 
soa()8. 73. 

Peroxide soap, 78. 

Petroff reagent, 117. 

Pfeilring reagent, 117. 

Phenol, n, 

Phenolphthalein, indicator, 38. 

Phenolphthalein, Using as indi- 
cator, 51. 

Phenols, Soaps containing, 11. 

Pinic acid, 22. 

Plodder^ 33. 

Potash from wood ash, 27. 

Potassium carbonate, 29. 

Powders, Light, 60. 

Powders, Scouring, 61. 

Powders, Shaving, 90. 

Powders, Soap, 56. 

Precipitation test for treated 
spent lyes, 110. 

Prevention of rancidity, 18. 

Pumice or sand soaps, 93. 

Purple shade in soap, 75. 



Rancidity of oils and fats, 16. 
Rancidity, Prevention, 18. 
Recovery of glycerine from spent 

lye, 106. 
Red oil, 15. 

Red oil, Saponified, 15. 
Resin acids. Total fatty and. 

Determination of in soap, 144. 
Ribot, ref., 20. 
Rosin, 22. 



241 



SOAP-MAKING MANUAL 



Rosinj Determination of in soap, 

144. 
Rosin saponification, 23. 
Run and glued up soaps, 69. 
Run soaps, 39. 



Sal soda, 29. 

Salt^ 30. 

Salting out, 30. 

Salt *Vckle." 37. 

Sampling crude glycerine, 162. 

Sampling for standard method, 
166. Note on, 184. 

Sampling oils and fats, 128. 

Sampling soap, 137. 

Saponification by ferments, 121. 

Saponification, Acid, 120. 

Saponification, Aqueous, 121. 

Saponification, Autoclave, 118. 

Saponification, Carbonate, 45. 

Saponification defined, 2, 105. 

Saponification, Lime, 118. 

Saponification number, 181-182. 

Saponification, Rosin, 23. 

Saponification, Various methods, 
105. 

Scouring and fulling soaps fur 
wool. 98. 

Scouring powders, 61. 

Scouring soap, 61. 

Semi-boiled laundry soaps, 49. 

Semi-boiled process, 44. 

Shaving cream, 90. 

Shaving powder, 90. 

Shaving soaps, 87. 

Silica and silicates. Determina- 
tion of in soap, 148. 

Silk dyeing, 102. 

Silk industry. Soaps used in, 
101. 

Slabber, 32. 

Smith method for moisture in 
soap, 138. 

Soap analysis, 137. 

Soap, Automobile, 41. 

Soap, Carbolic, 11. 

Soap, Castile, 79. 

Soap, Chip, *54. 

SoaCj Chip, cold made, 55. 

Soap, Chip, unfilled, 56. 

Soap, Cold cream, 78, 

Soap, Coloring, 75. 

Soap containing phenols, 11. 

Soap, Curd, 71. 

Soap, Defined, 1, 



Soap, Determination insoluble 

matter, 143. 
Soap, Determining glycerine in, 

149. 
Soap, Eschweger, 81. 
Soap, Floating, 62. 
Soap, Formaldehyde, 78. 
Soap for wool, Scouring and 

fulling, 98. 
Soap, Full boiled, 35. 
Soap, Iodine, 78. 
Soap kettle, 31. 
Soap, Laundry, 48. 
Soap, Liquid, 94. 
Soap lye crude glycerine, 113. 
Soap, Marine, 39. 
Soap, Medicinal, 76. 
Soap, Medicinal, less important, 

78. 
Soap, Mercury, 78. 
Soap, Metallic, 1. 
Soap, Peroxide, 78. 
Soap powders, 56. 
Soap, Pumice or sand, 93. 
Soap, Rosin settled, 50. 
Soap, Run and glued up, 69. 
Soap, Scouring, 61. 
Soap, Semi-boiled laundry, 49. 
Soap, Shaving, 87. 
Soap, Sulphur. 11. 
Soap, Tannin, 78. 
Soap, Tar, 11. 

Soap, Test for color of, 133. 
Soap, Textile, 98. 
Soap, Toilet, 65. 
Soap, Toilet cheaper, 68. 
Soap, Toilet, cold made, 72. 
Soap, Toilet perfuming and col 

oring, 73. 
Soap, Transparent, 82. 
Soap, Transparent, cold made. 

84. 
Soap used for cotton goods, 103. 
Soap used in the silk industry, 

101. 
Soap, Witch hazel, 78. 
Soap, Wool thrower's, 100. 
Soap, Worsted finishing, 101. 
Soda ash, 28. 
Sodium carbonate, 28. 
Sodium perborate. Use of in 

soap powders, 57. 
Soft soaps, 40. 
Soluble mineral matter detm. of 

in fats and oils, 173. Note on 

method, 187-188. 



242 



INDEX 



Solvay process, 28. 

Soya bean oil, 14. 

Spent lye, Recovery of glycerine 

from, 106. 
Spent lyes, 37. 
Spent lyes. Treatment of for 

glycerine recovery, 107. 
Splitting fats with ferments, 121. 
Standard methods of analysis for 

fats and oils, 165-196. 
Starch and gelatine, Determina 

tion in soap, 143. 
Stearic acid, IS, 19. 
Stearin, 2, 19. 
Strengthening change, 36. 
Strengthening lyes, 38. 
Strunz crutcher, 63. 
Sugar in soap. Determination of, 

150. 
Sugar, Use in transparent soap, 

83. 
Sulfate of alumina. Use of in 

spent lyes, 108. 
Sulphonated oils. 104. 
Sulphur soaps, IT . 
Sweating of soap, 62. 
Sweet water, 119. 
Sylvic acid, 22. 

T 

Talgol, 96. 

Tallow, 4. 

Tallow, Fullers' earth bleaching 
of, 4. 

Tallow, Improving color by ex- 
traction of free fatty acid, 6. 

Tannin soap, 78. 

Tar soap, IT. 

Test for color of soap, 133, 

Testing of alkalis used in soap 
making, 134. 

Textile soaps, 98. 

Titer, 130. 

Tank cars, Sampling, 166. 

Tierces, Sampling, 168. 

Titer, Standard method, 175. 

Titer, Note on, 189. 

Tingoil, Note one iodine, num- 
ber of, 189 

Toilet soap, 65. 

Toilet soaps. Cheaper, 68. 

Toilet soap. Use of hardened oils 
in, 96. 



Total alkali, Determination of in 
soap, 147. 

Total fatty and resin acids, De- 
termination of in soap, 144. 

Train oils, 20. 

Transparent soap, 82. 

Transparent soap. Cold made, 
84. 

Troweling soap, 52. 

Tsujimoto, ref., 20. 

Tubes for transparent soap, 85 

Turkey red oil, 104. 

Twaddle scale, 25. 

Twitchell method for rosin, 145. 

Twitchell process, 113. 

Twitchell process. Advantages. 
113. 

U 

Unsaponiflable matter, Determi- 
nation of in oils and fats, 132. 

Unsaponiflable matter, Determi- 
nation of in soap, 148. 

Unsaponiflable matter, determ- 
ination of by standard method, 
176. 



Vacuum Oven, Standard, 176. 
Vegetable oils, 6. 

W 
Water, 29. 
Water, Hard, 29. 
Witch hazel soap, 78. 
Wool thrower's soap, 100. 
Worsted finishing soaps, 101. 



Zinc oxide, Use of in autoclave 

saponification, 120. 
Zinc oxide, Use of in soap, 33. 



243 



LITERATURE OF THE 
CHEMICAL INDUSTRIES 



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A list of standard books relating to soapmaking 

and allied industries. 

Published and For Sale by 

D. VAN NOSTRAND COMPANY 

Publishers and Booksellers 
8 WARREN STREET NEW YORK 



Askinson, George W. Perfumes and Cosmetics. Their 
preparation and manufacture. Fourth Edition, trans- 
lated from the German, and revised with additions by 
W. L. Dudley. 32 illustrations. 6%x9y2. Cloth. 354 
pp. New York, 1915. $5.00 

Chalmers, T. W. The Production and Treatment of 
Vegetable Oils. Including chapters on the refining of 
oils, the hydrogenation of oils, the generation of 
hydrogen, soap making, the recovery and refining of 
glycerine, and the splitting of oils. 95 illustrations, 
9 folding plates. 8x11 1^. Cloth. 163 pp. London, 
1919. $7.50 

Deite, C. Manual of Toilet Soap-Making. Comprising 
toilet soaps, medicated soaps, and other specialties. 
Second Revised Edition. 85 illustrations. 6y^xl0. 
Cloth. 356 pp. London, 1920. $7.50 

Ellis, Carleton G. The Hydrogenation of Oils, Cata- 
lyzers and Catalysis and the Generation of Hydrogen 
and Oxygen. Second Edition, thoroughly revised and 
enlarged. 240 illustrations. 6^4^93^. Cloth. 767 pp. 
N. Y., 1919. $7.50 

Fischer, M. H. Soaps aud Proteins, Their Colloid 
Chemistry in Theory and Practice. With the collabo- 
ration of G. D. McLaughlin and M. O. Hooker. 114 
illustrations. 6x9%. Cloth. 281 pp. New York, 
1921. $4.00 



>^ 



Holde, D. The Examination of Hydrocarbon Oils, and 
of the Saponifiable Fats and Waxes. Translated from 
the Fourth German Edition by Edward Mueller. 115 
illustrations. 6^x914. Cloth. 499 pp. N. Y., 1915. 

Net, $5.00 

Hurst, G. H. Soaps. A practical manual of the manu- 
facture of domestic, toilet and other soaps. Second 
Edition. 66 illustrations. 6x8^. Cloth. 385 pp. 
London, 1907. $6.00 

Hurst, George H., and Simmons, W. H. Textile Soaps 
and Oils. A handbook on the preparation, proper- 
ties, and analysis of the soaps and oils and in textile 
manufacturing, dyeing and printing. Third Edition, 
revised. 12 illustrations. 5^x8^. Cloth. 212 pp. 
London, 1921. $4.00 

Keller, T. Cosmetics. A handbook of the manufacture, 
employment, and testing of all cosmetic materials and 
cosmetic specialties, with numerous recipes. Trans- 
lated from the German. Third Edition. 5x7j/2. Cloth. 
264 pp. London, 1920. $3.50 

Koppe, S. W. Glycerine. Its introduction, Uses and 
Examination. For chemists, perfumers, soapmakers, 
pharmacists, and explosives technologists. 7 illustra- 
tions. 5^x75^. Cloth. 260 pp. New York, 1915. $3.50 

Lamborn, L. L. Modern Soaps, Candles, and Glycerin. 
A practical manual of modern methods of utilization 
of fats and oils in the manufacture of soaps and can- 
dles, and the recovery of glycerin. 228 illustrations. 
6^x914. Cloth. 708 pp. N. Y., 1906. $10.00 

Murray, B. L. Standards and Tests for Reagent Chem- 
icals. 6x9. Cloth. 400 pp. New York, 1920. $3.00 

Parry, Ernest J. The Chemistry of Essential Oils and 
Artificial Perfumes. Vol. I, Monographs on Essential 
Oils. Fourth Edition, revised and enlarged. 51 illus- 
trations. 6^x10. Cloth. 557 pp. London, 1921. $9.00 

Vol. IL Constituents of Essential Oils, Synthetic 
Perfumes and Isolated Aromatics, and the Analysis 
of Essential Oils. Third Edition, revised and enlarged. 
Illustrated. 351 pp. London, 1919. $7.00 



Partington, J. R. The Alkali Industry. 63 illustrations. 
5j/ix8^. Cloth. 318 pp. London, 1918. $3:00 

Rogers, Allen. Industrial demistry. A manual for the 
student and manufacturer. Third Edition, thoroughly 
revised and enlarged. 377 illustrations. 6j^x9^. 
Flexible fabrikoid. 1255 pp. New York, 1920. $7.50 

Scott, Wilfred W. (Editor). Standard Methods of 
Chemical Analysis. A manual of analytical methods 
and general reference for the analytical chemist and 
for the advanced student. Second Edition, revised, 
with additional tables. 142 illustrations, 3 color plates. 
7x9%. Cloth. 900 pp. N. Y., 1917. $7.50 

Simmons, W. H. Fats, Waxes and Essential Oils. 

In Press. 

Simmons, William H. Soap. Its composition, manufac- 
ture and properties. 11 illustrations. 4}ix7%. Cloth. 
133 pp. London, 1916. $1.00 

Simmons, W. H., and Appleton, H. A. The Handbook 
of Soap Manufacture. 27 illustrations. 6x9. Cloth. 
166 pp. London, 1908. $4.00 

Van Nostrand's Chemical Annual. Edited by John C. 
Olsen. A handbook of useful data for analytical 
manufacturing and investigating chemists and chemi- 
cal students. Fourth Issue, enlarged. 5x7j4. Flexi- 
ble fabrikoid. 785 pp. New York, 1918. $3.00 

Watt, A. Art of Soapmaking. A practical handbook of 
the manufacture of hard and soft soaps, toilet soaps, 
etc. Seventh Edition, revised and enlarged. 43 illus- 
trations. 5j4x7y2. Cloth. 323 pp. London, 1918. 

$4.00 

Wright, C. R. A. Animal and Vegetable Fixed Oils, 
Fats, Butters, and Waxes; Their Preparation and 
Properties, and the Manufacture Therefrom of Can- 
dles, Soaps, and Other Products. Third Edition, re- 
vised and greatly enlarged by C. Ainsworth Mitchell. 
185 illustrations, 3 plates. 6x9. Cloth. 953 pp. Lon- 
don, 1921. $16.50 



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